Hammer & Sear Fitting:

[10851Man]

Greetings,

Got a few questions I wanted to throw out to all of you. I just finished restoring my 1927 Colt Pistol (Argentine Model made by Colt) that I will be using to replace my 1917 production 1911 duty pistol.

I replaced the barrel, bushing, link, pin, extractor, firing pin, firing pin stop, hammer & sear pins and all the springs. I am using the 16 lb recoil spring with a 23 pound mainspring.

The original trigger (fully machined one-piece trigger/bow assembly marked 'RA') was short and very sloppy in the frame. I replaced it with a C&S Long Aluminum Match Trigger with a smooth contact face. This trigger measured .921" tall and required reducing its dimension to .915" for a good fit.

I keep my 1911's all original, so I replaced the original wide spur hammer with one from Brownell's made by EMC. Very nicely machine hammer with no parting lines. The first wide spur hammer I bought was a casting and it just didn't look right. Along with the new hammer, I used one of Nowlin's Factory Enhanced Sears with a pre-cut primary sear surface. Nice piece.

I cleaned up some rough surfaces on the hammer with a stone. I found a tiny 'burr' in the half-cock notch, which I cleaned up with a tiny file and polished with 600 grit paper around a dulled pocketknife blade. The hooks looked good, except for some small tool marks on their surfaces. I cleaned up the mating surfaces of the hooks with a sharp, square hard Arkansas stone, using the flat surface below the hooks as a guide. I cleaned the hooks just enough to remove the Parkerizing finish and the light tool marks. I also polished the flat surface under the half-cock notch until it was smooth.

The sear looked really nice, although the primary engagement surface was wider than any of the good used sears I have in stock. I felt a rough edge on the edge of the engagement surface, so I applied a very light, narrow 45° (approximate) angle to this surface until the rough edge was smooth. I found a similar rough edge on the flat surface that contacts the thumb safety. This was also polished with a stone.

With the pistol assembled and a light coating of CLP on the working surfaces, I notice some slight 'creep' in the otherwise perfect trigger. At first I though I had stoned my hammer hooks out-of-square, but I tried 4 different (used) sears and every one of them eliminated every bit of the creep.

The hammer pin is .1575" in diameter and a nice fit in the frame. The sear pin is .1105" in diameter and fits nicely in the frame. There is a slight 'wiggle' of the pin when the weapon is dry-fired as a little oil is pushed out between frame and pin. Dad and I often make out own custom-sized pins for these projects, but I evaluated this against a brand new Sig 1911 that I have here in stock and the Sig sear pin is loose enough that movement can be seen!!!

My weapon passes all the requisite safety checks for hammer follow, disconnect function, thumb safety engagement, etc.

I asked my Dad about it (he was an armorer in Korea in the 1950's) and he said the best thing to do is just shoot it until it is Smooth.

In all the years I have worked on these pistols as an armorer, I have never had to replace a hammer and sear in a duty pistol, although the process was demonstrated in the 1911 Armorer’s course. I have built a few 1911's for people over the years and always installed a matched hammer/sear/disconnector assembly with excellent results.

I would greatly appreciate your input on this subject. Thanks very much...Robert

[log man]

Not knowing the hammer hook length leaves the question. Creep as you know is the feeling or perception of the sear nose dragging out from under the hammer hooks. Could actually be a couple of other things, trigger bow dragging in the track, disconnector ridding a rough surface in the slide relief. Or it could be the engagement surfaces of sear and hammer. Increasing the relief angle on the sear will often eliminate creep.

This is germane and from a previous post.

The importance of the hook face being square to the flat is just to maintain the original angle as they are cut with an end mill that has straight sides. What's relative is where does the hook face point when extended towards the hammer pivot hole. Para and Kimber will intersect the center point, while most others, and good, will point to the top of the hole. The sear should always and is the original design, be neutral so it neither raises nor lowers the hammer. Geometrically this means a line through the sear pivot and touching the sear nose is square with the face. If the hammer hooks are like Para's old hammer the match is parallel, contrary to most this is not good, the sear slips out easy enough, but is dragging the whole way and and follow will begin as the pull approaches 2#. The hammer hooks face should point to the edge or slightly lower, but above the center point and have a radius on the tips that contact the sear about .002"-.003", just a deburr and smooth. And if they are about .020" in length or less they will land right on top of the sear face, good, now when the trigger is pulled the sear will not move until the pull weight is achieved and will snap out crisply. If the hammer hooks should be long and pass the sear face then that would be captive, but if they land on top then it is aggressive.

With what I've written in mind, study the two configurations.

http://i472.photobucket.com/albums/rr85/logpics/20081217_2.jpg

http://i472.photobucket.com/albums/rr85/logpics/20081212_3.jpg

http://i472.photobucket.com/albums/rr85/logpics/20081218_2.jpg

LOG[/QUOTE]

[10851Man]

Log,

Thanks for the photos. Very good deatil indeed. I will have to pull the gun apart and measure everything tonight. The hammer hooks were not altered much at all, other than some light polishing.

One thing I did notice (on the new hammer) is the 'flat' surface at the edge of the hooks. On the original 1927 hammer, the rounded edge of hammer and the hooks form a sharp edge. One the new hammer, there is a small 'flat' stoned onto the point at which the rounded portion of the hammer (which the sear rides along during cocking) and the flat surface of the hammer hooks.

Now, just for clarification, when we talk about hammer hook depth, we are talking distance from outermost edge of hook surface to the flat under the hooks???

Thanks again...Robert

[log man]

As stated in the post .020" hook length is normally a good length to use, .018" and even .016" work well for light short pull triggers, but may not be best for carry. The hook length or depth is referring to the engagement face surface, from where it begins and ends. The area that the sear contacts. Since the sear nose is +- .030" the hammer hook tips should land on top of the sear nose engagement surface, not past it.

LOG

[niemi24s]

Hi Log:The importance of the hook face being square to the flat is just to maintain the original angle as they are cut with an end mill that has straight sides.Do you know of anybody that makes a hammer today with the Ordnance spec (derived) angle of 84.0° 86.0° between the hooks and adjacent flats?

Cheers

[10851Man]

Thanks....I will check that tonight. Just off the top of my head, I would have to say the hooks on my new hammer are consistent with all of the used ones I have in stock...Robert

[John]

Have you created a break-away angle on the sear?

[log man]

Hi Log:Do you know of anybody that makes a hammer today with the Ordnance spec (derived) angle of 84.0° between the hooks and adjacent flats?

Cheers
No. I have not seen this, but have not ordered and checked that many different brands. Would think only a Colt or other mil-spec type 1911 could possibly still do that. In fact in the prints that I've seen there isn't any indication that it isn't 90 degrees, and is +- .030". Which would make it captive. The angle to the flat doesn't do anything in regards to captive engagement, the alignment of the face in regards to the pivot center line and hook length is/does.

[10851Man]

Have you created a break-away angle on the sear?

I have not altered the sear's primary angle. It looked good to my eye when mated to the hammer outside the frame. I cut a 45° clearance bevel on the leading edge of the engagement surface to remove a shap edge. I didn't narrow the primary angle much at all (if any) when doing this, as my cut dressed an area past the primary angle (where the edge was) and not on the primary angle surface itself...Robert

[niemi24s]

Hi Log:

Just noticed I'd mistyped the angle - it's 86.0°, not 84°.In fact in the prints that I've seen there isn't any indication that it isn't 90 degrees. . .The angle's not given directly on any of the blueprints I have either, but a little math shows it to be not 90°, but 86° as shown here (without the math): http://i129.photobucket.com/albums/p232/niemi24s/P8050001d.jpg

I'm guessing JMB or the Army wanted it to be a little on the captive side.

But I can see (even not being a machinist) a 90° one would be lots easier to make - I think.

Cheers

[log man]

Hi Log:

Just noticed I'd mistyped the angle - it's 86.0°, not 84°.The angle's not given directly on any of the blueprints I have either, but a little math shows it to be not 90°, but 86°.

I'm guessing JMB or the Army wanted it to be a little on the captive side.

But I can see (even not being a machinist) a 90° one would be lots easier to make - I think.

Cheers
Yes, the tooling is standard and could cut the hooks at any angle relative to the pivot hole center line. There is absolutely no reason the hook face cannot be at any angle desired. To get a square (sharp) corner and an 86° included angle, the cutter, end mill, would have to be ground with that angle, it could of course be done on a surface grinder as well and the stone would have to be dressed to the included angle desired. Since the "flat" hasn't any function in operation it's relevance to the hook face is questionable. This poses an additional problem in maintaining and having on hand a hand stone with a matching corner to clean up and polish an acute angle between flat and hook face there could only be two corners instead of four that match. Square corners no matter there relation to the pivot center line just makes a whole lot more sense.

LOG

[niemi24s]

When I first worked up that drawing about a year ago, I was really surprised at the angle between the sear nose and the hooks. So surprised, in fact, I redid all the work a couple more times to see if I'd goofed somewhere.

Didn't find any goofs, but that doesn't mean I didn't make any.

I then made the mistake of looking at how the sear nose & hooks made contact on my Bullseye gun. Looked with my 60X shop microscope. I'll never do that again - it was really scary looking! :D

Cheers

[10851Man]

I have been told the interference angle is designed to make the area self-cleaning...Robert

[log man]

I have been told the interference angle is designed to make the area self-cleaning...Robert
That is misinformation, 10851 Man, as this is the design intended to keep the sear and hammer cocked during hard dropped slides and rapid fire, it doesn't follow down to less than 2# trigger pull. If the sear face and hammer hook face where parallel or more passive, follow would be the norm. And it would stay clean either way.

LOG

[10851Man]

I do not think the interface was 'designed' expressly for its self-cleaning properties, but I think it could be an unintended attribute....Interference angles are present in lots of machinery for their self-cleaning properties...Robert

[10851Man]

So, let's say that the hooks measure around .020"-.025" or so....then what would be an ideal width of the primary sear surface???

I have some good used (Colt) hammers and sears here that have very little surface across the edge of the sear....Robert

[log man]

The entire sear nose should be .025"-.030" the hammer hook tips should land on the sear face and the corners of the hooks that contact the sear face should be broken. The actual engagement is quite small and from the hammer hook tips back to the relief angle edge should be no more than .010", for a crisp trigger. By laying a .020" shim on the hammer flat against the hooks a stone can be used to uniformly lower the hooks to .020".

Adjusting the sear spring to about a pound on each the left and center leaf will yield a 3# +- trigger pull.

LOG

[10851Man]

Thanks, Log....

That's a great description. I will check that later on tonight and post some measurement....maybe I will shoot some photos of these parts.

I'm not looking for anything less than maybe a 5-6 pound pull. Just need to eliminate the creep.

Ironically, my trigger was perfect with the original 1927 hammer and sear, even though the hammer hooks had made small indentation in the sear surface. I just decided to upgrade all the parts based on the age of this weapon...Robert

[log man]

Hi Niemi,
Have to admit I hadn't payed a whole lot of attention to the spec. drawings we both are looking at and I clearly see the 32°45' and 53°15' for the 86° total. I've also stoned this configuration square in the past which brings the extended line from the face towards the pivot hole closer to the hole edge, and a less aggressive engagement.

LOG

[niemi24s]

I kind of figured 90° may have been sort of a "default angle" because while stones are available with 60° and a few other corners, nobody ever came out with one with an 86° corner - at least that I know of.

I suppose if somebody absolutely had to have one, maybe a 90° stone could be dressed with a diamond wheel and a surface grinder?

Cheers

[John]

I'm not looking for anything less than maybe a 5-6 pound pull. Just need to eliminate the creep.

From "The Poor Man's trigger job"

Lay the sear on the stone with the convex curve facing up, so that the backside of the primary angle is on the stone. Place the .020 feeler gauge under the legs, and push the sear along the stone from bottom to top to create a light breakaway angle on the back of the sear. Be careful to keep the legs on the feeler gauge. When the dressed line on the back of the sear is roughly 1/4th the width of the primary angle...stop.

[10851Man]

Thanks for that John....

I took a really close look at the pistol last night. I haven't measured everything just yet, but I did notice a few things.

The hammer hooks are nicely dressed and appear to be square. I haven't broke the outer edge of the hooks yet (as Log has suggested) but that's in my future plans to be certain. When I stoned the hooks (to remove the roughness and tool marks) I did so with a brand new stone without any edge radius; a very sharp, true 90° angle. I worked the hooks using the flat area beneath the hooks as a guide. Every few strokes, I would apply Dykem for reference and rehone. I also dressed the half-cock notch to remove some roughness in there.

From my Armorer’s training, I was told to use only a hammer hook squaring file with a safe edge to dress the hooks and to never use a stone, but the finish with a file just isn't as smooth.

I thought that perhaps I might have cut the hooks incorrectly and this was responsible (at least in part) for the creep I was experiencing. When I swapped in a couple of different, used sears, the creep disappeared. When I swapped hammers (I still have the original, but well-worn 1927 wide spur hammer and a few others) the creep returned only when I installed the new Nowlin pre-cut sear.

There had to be something about that Nowlin Sear. The primary angle doesn't look very smooth under magnification and it is certainly (without taking the time to measure) wider than the .030" mentioned in some of these posts.

Based on these observations and from what I have read, re-stoning the primary angle of the sear would be in order, but I don't have a sear jig. I have long thought that if the angle is correct and only needs to be polished, then one could use feeler gauges to hold the primary angle in correct relation to the stone, but this wouldn't be easy or all that accurate.

In the end, I think it is the sear that needs some work here to be certain.

One thing I noticed was a difference between the 1927 hammer and the replacement hammer. On the 1927 hammer, the curvature of the hammer (that the sear rides along during cocking) meets the outer edge of the hammer hook at a sharp point. One the replacement hammer (and several others I have in stock) the curvature meets the outer edge of the hook with a distinct flat. Not a huge difference, but something I did notice.

Thank you all for your replies to this thread. More on this topic later today...Robert

[10851Man]

Ok, one question from the 'poor man's trigger job' thread.

I am aware that you want to stop stoning when the dressed line on the back of the sear is roughly 1/4 the width of the primary angle, but what do you do if your primary angle (at this point) is still wider than the .030" that I have heard mentioned???

How wide (or narrow) do you want the primary angle surface to be when you are finished with it??? I have heard everything ranging from .020" to .047" and almost every measurement in between.

Could we clarify this???...Robert

[log man]

Ok, one question from the 'poor man's trigger job' thread.

I am aware that you want to stop stoning when the dressed line on the back of the sear is roughly 1/4 the width of the primary angle, but what do you do if your primary angle (at this point) is still wider than the .030" that I have heard mentioned???

How wide (or narrow) do you want the primary angle surface to be when you are finished with it??? I have heard everything ranging from .020" to .047" and almost every measurement in between.

Could we clarify this???...Robert
If the sear is in spec. the uncut primary angle face will be .030"+- the secondary angle should approach 1/3 so that leaves .020" of primary, if the hooks are .020" that leaves .010" of engagement and a good place to be, fine tuning at this point will give a crisp trigger pull.

http://i472.photobucket.com/albums/rr85/logpics/Image2.jpg
LOG

[10851Man]

Log Man,

Thank you for the blueprint and the explanation. That is now crystal clear to me. I appreciate that. I have some sears that only have a .015" wide primary angle.

Question...In the case of my Nowlin pre-cut sear that has the correct angle but the surface isn't all that smooth, has anyone found a way to mimic the primary sear angle for light polishing???

Since I can eliminate all my creep with a used sear, would that indiacte I did my hammer hooks correctly???...Robert

[log man]

Polishing the marks out of the primary angle without a jig can be done, if you have the skill to do so. Some will hold in a vice with just the face parallel to the top of jaws and slide a stone over it. The problem is left to right contact and really getting a repeatable position is iffy. Ya can't play ball well with a rock, ya need the tools. There are inexpensive sear jigs that are preferred by many GS so what's $30.00 to get it right and have it for future use. I use a Power Custom Series I and it will last a couple life times. Here's a picture of it with a sear in place and shows how I position the stone for a neutral primary angle. The thrid picture shows a way of cutting the secondary angle.

http://i472.photobucket.com/albums/rr85/logpics/20090107_2.jpg

http://i472.photobucket.com/albums/rr85/logpics/20090107_1.jpg

http://i472.photobucket.com/albums/rr85/logpics/20090331_1.jpg

LOG

[10851Man]

Fantastic Log.....I will be taking a closer look at this pistol tonight. Thank you very much for your time and expertise!!!...Robert

[10851Man]

Just based on looking at the pre-cut Nowlin sear, I see two things wrong:

1.) The primary angle appears correct, but is not smooth.

2.) The primary angle is much too wide

Am I correct that you should break the edges of the hammer hooks???

[log man]

Just based on looking at the pre-cut Nowlin sear, I see two things wrong:

1.) The primary angle appears correct, but is not smooth.

2.) The primary angle is much too wide

Am I correct that you should break the edges of the hammer hooks???

Yes, post #2, .003" radius on the corner of the hooks that contact the sear face.

LOG

[Jerry Keefer]

Folks;

Here are some photos of the set up that I have settled upon to get perfect hooks every time. I have tried hundreds of methods over the years and this is by far the best, so far. It's not cost effective for the hobbiest, but for you guys who are in the business, it works super great... and allows for adjustments that can be measrued in the seconds...


Jerry

http://i604.photobucket.com/albums/tt128/jerrykeefer/balldetent007.jpg http://i604.photobucket.com/albums/tt128/jerrykeefer/balldetent008.jpg

[10851Man]

Ok....Now I was thinking....You could 'break' the edges of the hook, closest to the sides of the hammer with relative ease. Would you want to break the edge of the hook nearest the flats that are used to shorten the hammer hooks???

I may not be using the correct terminology, but I am referring to the edge that the sear would slide past as it engages with the hook, or, should you leave this area sharp???

Thanks...Robert

[log man]

AAhh... That would be a yes as per post#2 and #29. The hook tips that make contact with the sear face (primary angle surface) a .003" radius.

LOG

[10851Man]

Should I break the edge along the side of the hooks too???

[10851Man]

Ok...

I really got to looking at the fire control parts today and that Nowlin Pre-Cut Sear was ROUGH to say the least!!! The primary angle looked good, but the face of the sear actually looked corrugated when magnified. It gave me the impression the sear was cut by machine and the tool was chattering.

What I did, in the absence of a sear jig, is take one of my depth micrometers, which has a long, flat face and sides that are 90° to the lower surface and removed the measuring pin. This turned the tool into an anvil or lathe black if you will. Measurements confirmed the tool was square.

I laid the sear against the side of the tool and trapped it with a small 'C' clamp, using a piece of business card to keep from marring the sides. Since my approach was based on the assumption that the machined sides of the Nowlin sear were square, I conducted an experiment.

Once I 'eyeballed' the angle of the primary surface above the anvil and squared it up, I confirmed this by using a feeler gauge on top of it with a .002" gauge on top the tool's anvil. Then, I inked the primary angle and dragged a feeler gauge over it, which instantly de-inked the sear across the entire surface, leaving only the low spots filled with ink.

With a light Teflon spray lube, I stoned the sear's primary angle with a white (hard) Arkansas stone (brand new and sharp) until the corrugated marks vanished. The primary angle surface was .033" wide before I started and it was .035" wide when I was finished.

As you may recall, I stoned my hammer hooks with an Arkansas stone to remove any machine marks. I used the anvil of my depth micrometer and some fine valve grinding compound to lap the hooks and flats. They immediately colored a light gray across the face and this showed a 'true' 90° angle, as lapping took place in the deep intersection of hammer hook and flat.

A quick measurement of the hooks revealed they were between .028" and .031" deep.

Now, if I remember my Armorer’s training from Log, 1911 Tuner, John and others here, I want to stone the hooks to .025" by 'flattening' the point where the curvature of the hammer's journal and the edge of the hook intersect. I also want to break the edge of the hooks by about .003" with my Arkansas stone.

The sear will need to be pushed along the stone with a .020" feeler gauge under it to create the secondary angle. IIRC, Log and 1911 Tuner mentioned the width of the primary angle should be about .020" when the secondary angle has been cut, so I will shoot for that rather than try to 'eyeball' the secondary angle at about 1/4th of the primary angle.

Here are a few photos...Robert


http://i575.photobucket.com/albums/ss196/10851Man/Weapons/HammerHookDetail.jpg

http://i575.photobucket.com/albums/ss196/10851Man/Weapons/HammertoSearInterface.jpg

[kenhwind]

Well I'm confident in my ability to do this, but I do have a hammer sear jig.
After following this thread I decided that my Supers trigger pull left something to be desired. seems in how I never finished it in the first place.
Actually it wasn't that bad.
Well I had ordered a new Colt sear spring and it was installed, so I disassenbled the gun.
I had previously installed a Berryhill Commander hammer. So what I did today was polish the hammer hooks and shorten them using my 0,020 shim. (Hmmm! thought I did that)
The sear and hammer contact looked good so I then polished the sear nose. There was still enough secondary angle there.

Now what I did was bust all the edges on the hammer hooks with the xtra fine stone. (The instructions tell ya to do that, Huh!)

Very nice and clean trigger, with a Wilson Combat factory rated maunspring.

[10851Man]

Ok....Trigger pull is good...creep is almost totally gone, but if you pull the trigger super slow, you can still feel it. Based on his work with Mil-Spec guns in the Army, Dad thinks I should just shoot it to break everything in rather than try to get it perfect right out of the box.

What do you experts think???...Robert

[log man]

What dad says has some merit in time. Here's what I do I get in good light and get a focus on the sear nose through the strut slot in the hammer, cocked of course and I watch for any movement when I pull the trigger slow even if I don't feel it. If I see it move before the hammer drops, it comes back apart and I do some studying and re-work til I get what I want 2#, no creep. The lighter the trigger the harder it is.

LOG

[kenhwind]

OK, the .38 Super passes muster sofar.
The .45 has an issue, which I'm sure I already know the answer for.
Seems in how we have a hammer and sear thread going I'm gonna throw this in the pot.

The hammer on my .45 falls to half cock using dummy rounds.
The gun is well used works quite well but has been shot a lot.
16# recoil springs are on the way.
I just installed a new Colt sear spring, and a new Wilson factory rated mainspring.
The mainspring that came out looks like it might be for a Gold Cup.

Install a 16# recoil spring; OK this is gonna be a done deal.
Replace sear?
Replace hammer?

Input please.

[10851Man]

Here is a good story from my "Strange but True" file....

I have a 10mm Delta Elite here that I am cleaning up and re-springing for a gentleman. It has one of the best triggers I have ever pulled, so when I stripped it down, I was anxious to see the sear. When I removed it, I was surprised.

There was a big chunk missing out of the middle of the sear and the primary angle showed a LOT of wear. I don't think the gun has ever been lubricated.

Funny how the trigger pull is so smooth and crisp, isn't it???...Robert

[10851Man]

I'm shooting for a 5 to 6 lb trigger, Log Man...Does that make a difference??? I thought your post referred to a 2 lb pull???....Robert

[log man]

OK, the .38 Super passes muster sofar.
The .45 has an issue, which I'm sure I already know the answer for.
Seems in how we have a hammer and sear thread going I'm gonna throw this in the pot.

The hammer on my .45 falls to half cock using dummy rounds.
The gun is well used works quite well but has been shot a lot.
16# recoil springs are on the way.
I just installed a new Colt sear spring, and a new Wilson factory rated mainspring.
The mainspring that came out looks like it might be for a Gold Cup.

Install a 16# recoil spring; OK this is gonna be a done deal.
Replace sear?
Replace hammer?

Input please.
I'll make some assumptions that the hammer doesn't follow when the trigger is held back. Which indicates the center leaf needs more tension to resist trigger bounce. The left leaf can be relaxed a little so the pull weight isn't increased. It's a balance.

LOG

[log man]

Here is a good story from my "Strange but True" file....

I have a 10mm Delta Elite here that I am cleaning up and re-springing for a gentleman. It has one of the best triggers I have ever pulled, so when I stripped it down, I was anxious to see the sear. When I removed it, I was surprised.

There was a big chunk missing out of the middle of the sear and the primary angle showed a LOT of wear. I don't think the gun has ever been lubricated.

Funny how the trigger pull is so smooth and crisp, isn't it???...Robert
The missing part is Colt's way of protecting the sear engagement surface and is common in Colt's higher end guns, Gold Cup, etc.

[log man]

I'm shooting for a 5 to 6 lb trigger, Log Man...Does that make a difference??? I thought your post referred to a 2 lb pull???....Robert
Ah... yeah, a 5#-6# will be a lot easier to get creep free. Later, maybe.

LOG

[10851Man]

Definitely the sear Log Man. Change the sear and creep is gone. Who makes the best pre-cut sear???? I know it will need a relief angle, but I am not happy with this Nowlin sear at all. It has been 'off' from the minute I installed it.

Could you give me a better explanation about what you meant in the post about the Gold Cup??? That sear is beat up bad, but works great!!!

[log man]

Definitely the sear Log Man. Change the sear and creep is gone. Who makes the best pre-cut sear???? I know it will need a relief angle, but I am not happy with this Nowlin sear at all. It has been 'off' from the minute I installed it.

Could you give me a better explanation about what you meant in the post about the Gold Cup??? That sear is beat up bad, but works great!!!
I like EGW's hard sear it is very symmetrical and square, the sear engagement surface does need to be polished and the secondary angle added. They don't do it so the smith can. The sear in the Gold Cup and others has the center lowered so it gives the half cock more clearance when the over travel is set close and if it should fall to half cock the engagement is less likely to be damaged.

http://www.brownells.com/aspx/NS/store/productdetail.aspx?p=6127&st=EGW%20sear&s=

LOG

[10851Man]

I notice the lowered portion in the middle, but this area is marked by a deformation like a chip of metal passed through the hammer/sear interface...Robert

[log man]

I notice the lowered portion in the middle, but this area is marked by a deformation like a chip of metal passed through the hammer/sear interface...Robert
It probably was damaged by the hammer when it went to half cock.

LOG

[wichaka]

Been using Nowlins Pro-Match sears for years, haven't had a rough one, or odd cut one yet.

Which model are you using?

[10851Man]

Hey, Wichaka,

I got one of Nowlin's enhanced pre-cut sears....

[10851Man]

How much does a 'Log Man Mossy Oak Match Sear' go for????

[kenhwind]

I'll make some assumptions that the hammer doesn't follow when the trigger is held back. Which indicates the center leaf needs more tension to resist trigger bounce. The left leaf can be relaxed a little so the pull weight isn't increased. It's a balance.
Tried it with the trigger pulled and your assumption was right, so I switched back to the sear spring that was in it (GI I think). No hammer/sear bounce. If I'm not satisfied I can retrofit the Gold Cup mainspring too

thankyou

[10851Man]

I had forgotten how much fun a Gold Cup was to put back together...That tiny little spring in the sear is sure hard to find when it takes off.

Just a little piece of the red plastic spray tube off my WD-40 can keeps the sear/disconnector in place...Robert

[Hammerdown]

I've been reading this thread with great interest, and have been contemplating trying this on a "range only" gun, but I have a question: How are you measuring some of these extremely small surfaces and radii? With Vernier calipers? Feeler guages? How do you measure a .003" radius on the hammer hook tips? What about the width of the primary angle on the sear after you've cut the breakaway angle? Is this something you can get a caliper on with repeatable accuracy?

Forgive me if these are obvious questions to you guys, I haven't done any type of metal work that required this type of precision!

[Jerry Keefer]

[QUOTE=Hammerdown]and radii? With Vernier calipers? Feeler guages? How do you measure a .003" radius on the hammer hook tips?
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I wondered when some one was going to ask this...
The human eye can't even see or measure such a small dimension without the aid of a tool makers microscope..or othersuch optic.. A .003 radius is a .006 diameter circle..the average human hair is often less than .006
Dig out your compass and draw a .006 circle.. :)

Is this something you can get a caliper on with repeatable accuracy?
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No...it can be measured but not with average equipment..I am quite sure Log, speaking in general terms, means that you need to "barely" stone the corner to remove the burr and break the sharp edge somewhat from the hook. Only a very well equipped machine shop can make such a measurement... Frankly, I am not much good at hand work, and rely heavily on machines to achieve precision results.
Good observation...stay curious..

Jerry


Forgive me if these are obvious questions to you guys, I haven't done any type of metal work that required this type of precision.

[John]

All these measurements give me headache. I've never ever examined a sear under a magnifying glass (let alone a microscope) nor have I ever cared about dimensions. I do not know if I was lucky or what, but fitting a sear to a hammer is NOT rocket science.

[10851Man]

Gentlemen,

With the very small radii, I use a wire guage and compare based on visual reference. I visually estimated my firing pin hole chamfer at .010" wide, but when I actually put the wire guages up next to it, the width was much, much smaller.

I look at the hammer hooks under magnification and break the edge to the visual approximation of a .003" feeler gauge's thickness.

John,

The Nowlin Enhanced Factory Sear that I had looked rough to the naked eye and looked corrugated under a magnifying glass. I am also convinced that the primary angle was cut off-center...Robert

[10851Man]

Let's talk a little about fitting the sears with a pre-cut primary angle. I just bought one of the Nowlin factory Enhanced Sears. The primary angle just didn't look right and it was super-rough.

What's the correct or desired finish on these sears????

I know from tearing down a lot of 1911's that many times, the sears look awful, even with fantastic trigger pull.

I've been using a .020" wide primary surface with a .006" to .008" relief angle.

Input???...Robert

[niemi24s]

FWIW, the type of microscope Jerry referred to: The human eye can't even see or measure such a small dimension without the aid of a tool makers microscope..is also called a "shop microscope". Here's what an inexpensive one looks like: http://nationaloptical.com/products/shop/models/186.html

The measuring scale is built into the eyepiece and when the surface feature being measured is viewed, the scale's a part of what you see. I got one for about $75US on eBay a few years ago (similar to the Model 188 shown) to measure Brinell indenter ball depressions in bullet metal samples. With a 0.100" long scale having 0.001" divisions, measurements of small surface features are possible.

If the edges of the surface feature are sharp and distinct (and can be brought into simultaneous focus), it can be measured to the nearest 0.0005" with the 60X model.

Regards

[wichaka]

Hey, Wichaka,

I got one of Nowlin's enhanced pre-cut sears....

That's their low end MIM sear...I wouldn't touch that one for nothin'

[10851Man]

I know that now...

[10851Man]

Gentlemen,

I have been working on the hammer/sear mating in my 1927 Colt Argentine and I would like to ask a few questions.

In stock form, the 1927 Colt sear and 1927 wide spur hammer gave very 'crisp' trigger pull, although it was a little on the heavy side. The hooks on the 1927 hammer looked perfect and the sear was rounded somewhat.

During the restoration process, I replaced the hammer and sear as part of the rebuild. I used an EMC wide spur hammer from Midway which is of very good quality. I dressed the hooks to .026" and broke the edges with a hard Arkansas stone. The hooks were verified square against the anvil of a depth micrometer.

I used a Nowlin enhanced disconnector, Nowlin enhanced factory sear and a Cylinder & Slide long, adjustable aluminum smooth-face trigger with the adjustment screw removed.

The primary angle on the Nowlin sear was rough and actually looked corrugated under magnification. However, when hammer and sear were mated, the angled looked almost identical to the drawing posted earlier in this post. I cut a relief angle on the sear in accordance with the 'Poor Man's Trigger Job' and lightly polished the primary angle to remove the 'chatter marks' across its surface.

When I was finished, the width of the primary angle was about .020" and the width of the escape angle was approximately .006" overall.

The trigger pull was crisp, but if you pressed the trigger very, very slowly, you could feel a distinct creep as the sear 'dragged' across the hammer hooks.

I decided to replace the sear and tried another Nowlin (realizing it is the less desirable MIM variant) sear I had in stock for a friend's pistol. I ended up with the same creep that I had with the previous Nowlin sear. Interesting, when I installed the obviously worn, rounded 1927 sear, my trigger pull was a perfect 5 lbs with no creep.

I have since paid close attention to the condition of sears in pistols with a 'good' trigger pull. One of the 10mm Gold Cups we have in the department armory has one of the smoothest and best triggers you could ask for, with no follow. However, if you were to look at the sear, it would scare you. There is a 'chunk' missing out of the depression in the center of the primary angle and the edges that contact the hammer hooks are worn into a rounded profile. The sear also appears to have a relief angle on both sides of the primary angle, which leave a rather 'pointed' surface with which to contact the hammer hooks, not much more than .010" to .015" wide overall.

Several other Colt 1911's that I have access too exhibit the same type of wear and/or 'pointed' profile on the sear's primary angle and none of the guns I have in stock have a smooth, flat primary angle.

This leads me to ask you all a question about the sear's primary angle overall profile. Currently, I am using a sear with a .020" wide primary surface and a .005" to .008" wide relief angle, created by pushing the sear along an Arkansas stone atop a .020" feeler gauge.

Is the current, .020" wide, flat primary angle profile I am using considered to be 'correct' or should I reduce the width of the primary angle to more of a 'pointed' profile as I have found in several of these original, used 10mm and .45 Gold Cups???

I apologize or asking so many questions, but I am determined to correct this trigger pull issue once and for all.

Thanks for your time with respect to this matter...Robert

[log man]

This is a conundrum in understanding. Yes, the relief angle should be increased to obtain a creep free trigger, I want the hammer hooks to land on top of the primary sear face about .018" from the edge of the sear, that will be about .008"-.0010" past the primary and secondary intersection. Here's the conundrum, when the secondary angle is cut the way I've shown by sliding it on a shim and stone and is the common method, sometimes, because of individual sear profiles, it causes the sear nose to go deeper into the hammer hook corner, the answer is a more shallow relief angle that won't thin the sear nose so much, but will give the needed clearance. I use the Power Custom Series I sear jig for this as it is fully adjustable. Okay after cutting a secondary/relief angle break the point or corner generated by the two angles by holding the sear against the stone and dragging it on the secondary face and roll it across the line towards the primary face a few strokes.

In addition to all this the hammer hooks should bear equally on the sear face with both hooks

LOG

[Jerry Keefer]

[QUOTE=niemi24s]FWIW, the type of microscope Jerry referred to: is also called a "shop microscope".

Niemi; Here is a tool makers microscope..
http://i604.photobucket.com/albums/tt128/jerrykeefer/DSC00107.jpghttp://i604.photobucket.com/albums/tt128/jerrykeefer/DSC00285.jpghttp://i604.photobucket.com/albums/tt128/jerrykeefer/DSC00289.jpg

Jerry

[10851Man]

Thanks, Log....

I really appreciate your time, it's just hard for me to visualize this in my head. Is there any way you could post a sketch like the one that appears eariler in this post showing the hammer hook and sear interference fit??? Additionally, what are the minimum widths that are deemed 'safe' for the sear's primary angles???

On the 10mm Gold Cup I have in the department's armory, the sear has a very rounded, slightly pointed 'speedbump' profile and shallow hammer hooks that measure just over .018" overall. By studying this sear under magnification, it is quite obvious there are three distinct angles on the sear and the 'rounding' of the primary angle is due to wear.

There is a very distinct cut on both sides of the primary angle which leaves this area only about .010" to .015" wide overall. It is obvious that once the angle was cut, the nose of the sear was 'dragged' along the stone to 'blend' the three angles together. The nose of the sear is hitting the hammer hooks squarely about a 1/4th of the way across the hook face (towards the outside edge) with a thin, shiny line, about .010" to .015" in width.

It is apparent to me, after looking at the way these angles were cut, whoever cut them used the twin relief angles (on either side of the primary surface) to move the position and width of the primary angle across the sear's tip, much like the 15° and 60° stones will allow you to narrow and re-position the 45° valve seat angle in an overhead valve cylinder head.

After tearing down a lot of older Colts in inventory, I have noticed this sear profile in more than just a few weapons. In fact, the rounded 'speedbump' profile appears frequently in the older Colts and Gold Cups, as do the two distinct cuts on opposite sides of the primary angle.

Thoughts???...Robert

[10851Man]

Ok....

Take a close look at the photo that Jerry posted above. If you were to place the angle in the left of the photo (nearest the hammer hook) on the opposite side of the primary angle, you would have the 'speedbump' style 'triple' angle that I am describing. The outer angle tends to 'shift' the primary angle deeper under the hammer hooks...Robert

[niemi24s]

Hi Jerry:Niemi; Here is a tool makers microscope..
It certainly is! Mine's a toy compared to that one!! :p

Regards

[log man]

The point is the secondary angle doesn't need to be at a 45° angle to the primary and thins the nose more, when a 20° will give the needed relief and not thin the nose as much.

You don't want the hooks to pass the end of the primary angle unless you're trying for a heavy pull. What you may be seeing is the machining of the geometry of the sear as the area your pointing out is often machined to make the primary edges parallel.

LOG

[10851Man]

Log Man,

Do you ever prep sears for hire???...Robert

[log man]

Oh, Fresno, ever go to John's Incredible Pizza? I built and installed all the hundreds of feet of zany railings in the place, kind of a fun job.

Keep playing with all the information and you'll get it and the next one will go easier the dimensions quoted are seldom verified as you fit till you're happy and the fit proves out through safety checks.

LOG

[10851Man]

Yes!

Been to John's more than a few times. Nice work indeed! The Fresno County Sheriff's Gang Unit has its meetings there.

OK, I have a SARCO sear here that I never used. I set the primary angle using that little cheapo Ed Brown Sear Jig, then cut a relief angle as demonstrated in the 'Poor Man's Trigger Job,' by pushing the sear along my Arkansas stone under a .020" feeler gauge.

Then, I reset the jig and cut a relief angle 'by eye' on the front of the primary angle. I then dragged the stone lightly over each transition, just breaking the edge between the two angles and creating a perfect 'speedbump' profile, but maintaining a razor sharp primary angle, about .015" to .018" in width.

Based on your knowledge of these weapons, how does that profile sound to you from a safety and longevity standpoint???

Thanks...Robert

[log man]

Yes!

Been to John's more than a few times. Nice work indeed! The Fresno County Sheriff's Gang Unit has its meetings there.

OK, I have a SARCO sear here that I never used. I set the primary angle using that little cheapo Ed Brown Sear Jig, then cut a relief angle as demonstrated in the 'Poor Man's Trigger Job,' by pushing the sear along my Arkansas stone under a .020" feeler gauge.

Then, I reset the jig and cut a relief angle 'by eye' on the front of the primary angle. I then dragged the stone lightly over each transition, just breaking the edge between the two angles and creating an perfect 'speedbump' profile, but maintaining a razor sharp primary angle, about .015" to .018" in width.


Based on your knowledge of these weapons, how does that profile sound to you from a safety and longevity standpoint???

Thanks...Robert

Well, at least you didn't spend a lot to experiment. :) It may be fine, may be great, how does it feel. The Ed Brown Jig is a good choice. A curious thing about many mechanisms is the surfaces that make contact are the only ones that count. You look at and see some of the firearms that are made in third world and worse settings and they work well in spite of the rough appearance. What's important has been maintained.

LOG

[10851Man]

Log,

I talked with Dad last night about this and he gave me some insight into how they setup their Colt .45's for competition against the Honolulu Police Department in Hawaii in the 1950s.

After his return from Korea (Fox Company 25th Infantry 35th Regiment) Dad was stationed at Hickam Field. He worked in the armory and setup the unit's .45's for their annual competition against the Honolulu Police Department.

When I was showing Dad the sears I had been working on, he explained that the 'extra angle' that I am referring to is simply used to narrow the face of the sear's primary angle.

I setup an old SARCO sear that I have had laying around for a few years. Once I cut down the primary angle to around .018" to .020" overall width, all of the creep in the trigger was gone. Looking at the sear under magnification reveals the 'speedbump' profile I have seen on our department's Gold Cups.

Dad also gave me a neat tip that I wanted to share. He told me that they would inspect the sear periodically (in a fully assembled pistol) by holding the hammer back and pulling the trigger while looking in between the disconnector rail and the journal of the hammer. The primary surface of the sear can be clearly seen in this area.

Here is where I am at now. I have .026" hammer hooks, perfectly squared to 90° with a hammer file, smoothed with a stone and then lapped on a lathe blank with grinding compound.

My sear has a .020" wide primary angle with a light relief angle roughly .006" wide. I added a second cut to the sear on the opposite side of the primary angle, also about .006" in width and broke the edge between the three angles.

When the weapon is cocked, the sear is snapping into the hooks squarely. The hammer hooks are resting on the sear's primary angle at about the mid-point and the mark on the hooks indicate just the outer 3/4ths of the hooks are contacting the sear.

Inspection under magnification shows a good fit between hammer an sear.

The trigger pull is exactly where I like it; a bit on the heavy side, around 5.5 to 6 lbs but with no creep and instantaneous, surprise break.

I think I have it now. Thanks for all your help!!!...Robert

[niemi24s]

Hi Log & Robert:

Been following along with great interest and would like to capture what you've both said in the form of a pic (or two pics) showing both your processes and final results.

Here's a pic from a thread about 2 years old I'd like to use as a starting point: http://i129.photobucket.com/albums/p232/niemi24s/P077190002e.jpg If you're both willing and can find the time, let me know what modifications to make and I'll churn up a couple of new ones.

We could do this with PMs to avoid cluttering up the thread if you'd prefer.

Cheers to you both

P.S.: Each of the minor divisions on the graph paper is 0.001"

[10851Man]

Thanks!!!!

I am trying to get a photo of my sear, but I can't get enough resolution, even on 'Macro' at such a small item.

I will be glad to work on a sketch and I can email it to you, or post it in my Photobucket.

My sear profile is identical to the one posted in the microscope view above, except for the additional angle on the other side of the primary angle.

Again, this angle does nothing more than narrow the width of the primary angle...Robert

[log man]

The difficulty of getting a picture like this hand held is compounded by the fact the parts edge are not crisp, but it gives an idea of the discussion.

http://i472.photobucket.com/albums/rr85/logpics/20090601_7.jpg
http://i472.photobucket.com/albums/rr85/logpics/20090601_10.jpg

LOG

[John]

Ahhh excuse me for asking, but is it how a properly fit sear should fit the hammer hooks?

[log man]

Ahhh excuse me for asking, but is it how a properly fit sear should fit the hammer hooks?
Well, I couldn't get the camera in the gun so they are just propped, but close, it can be seen that if the sear nose is .030" and the hooks are .020" and the primary is about .010 then that's it, it can also be seen that the hook tips are what land/sit on the sear face.

LOG

[10851Man]

I had a Nornico .45 here a while back that would hammer-fall every so often. When I checked the hammer hooks for squarness, I found that had been cut to the point the tips were higher than the base and the sear was literally slipping off!!!

I replaced the hammer and fixed the problem. I also have a SARCO hammer in stock that isn't square either and no amount of filing/stoning could correct it. It's now a paperweight...Robert

[niemi24s]

Hi Log:

Great pix! Looks pretty close to the right hand one in my diagram - except the one in the diagram doesn't have the 0.002 -0.003 radius on the tips of the hooks.

S'matter of fact, with pix like that, who needs a diagram? :rolleyes:

FWIW, here's what a mid-spec Ordnance hammer & sear would engage before any work was done: http://i129.photobucket.com/albums/p232/niemi24s/P8040002d.jpg
Cheers

[dawsti]

Log is about right with that fit. My hammer sear relationship is about the same and it is 15 oz. with no follow in thousands of rounds. Of course the hammer is a Koenig and the sear is by Extreme Engineering and unaltered.

[10851Man]

Finally got my release right on this EMC wide spur hammer and Nowlin sear. I found that the primary angle on the sear was correct as ground, but needed polishing as it was very rough, almost corrugated under magnification. Once I got the surface smooth, I added a release angle and broke the edge between the two. I also used a fine lapping compound to mate the two surfaces.

The release is now immediate with no movement whatsoever. I just received my new Colt sear spring and I am curious to see what impact, if any, this has on my trigger pull weight...Robert

[10851Man]

Here are two pre-cut Nowlin sears, The one on the left was re-cut and polished by me and the one of the right shows the 'corrugated' factory finish on the primary angle...Robert

P.S. The Colt sear spring installed perfectly with no modification...

http://i575.photobucket.com/albums/ss196/10851Man/NowlinSearRight1.jpg

[10851Man]

By the way, the genuine Colt Sear and Disconnectors are by far the best I have seen. They have the smoothest finishes, especially the primary angle (under high magnifiction) of any I have recently tested...Robert