Hammer falls when slide closed

[stefanosg]

With some help from here I finished assembling my 1911. Everything seemed to work okay until I cycled the slide and released it with the slide release. The hammer then fell into the half cocked position. It does not happen all the time, but I'd say at least 75% of the time I tried it.

[log man]

I believe you're experiencing trigger bounce, increase tension on the center leg of the sear spring.

LOG

[Joshua M. Smith]

Did it do this before you took it apart, or do you know?

What changes were made?

Josh <><

[stefanosg]

Did it do this before you took it apart, or do you know?

What changes were made?

Josh <><
That was my SA in 9mm. It went back together just fine. I was fiddling with it to learn on. I was given an old frame and I thought it would be a hoot to build a frame for my AA conversion kit. If it is the spring tension, how do I change it? I don't want to just start bending stuff wrecklessly.

[Mgonz45]

That was my SA in 9mm. It went back together just fine. I was fiddling with it to learn on. I was given an old frame and I thought it would be a hoot to build a frame for my AA conversion kit. If it is the spring tension, how do I change it? I don't want to just start bending stuff wrecklessly.
Are you sure the sear/disconnector are in correctly and the trigger/sear/grip safety spring is correct ?

[log man]

1.Drop the slide with the trigger held back, if the hammer follows increase the tension on the left leaf of the sear spring.
2.Drop the slide with the trigger free, if the hammer follows increase the tension on the center leaf of the sear spring.

To adjust either leaf of the sear spring, look at it's present relationship with the others and flex and compare until you can tell it's changed a little, try it, repeat until properly adjusted.

LOG

[niemi24s]

There's also a blueprint of the sear spring in our Tech Issues section showing the leaf contours.

[Joshua M. Smith]

How long are the hammer hooks?

They should be .020" to .030". I prefer at least .025".

Do you have either an STI or Fusion grip safety installed without an adjustable trigger?

Make dang sure the disconnector and sear are installed properly.

Look forward to hearing the solution...

Josh <><

[stefanosg]

I watched the action a couple of more times and I have some more information on the problem. The hammer seemed to follow the slide. So I released the slide and held it so that it would close slowly. As I had suspected the hammer still followed the slide. I am not sure that I am getting the spring slap mentined earlier. It looks as though the hammer is not getting fully cocked by the slide. Keep in mind also that it is an AA conversion kit on top, not a regular .45 slide.

[stefanosg]

Here is some more information. I draw the slide back and leave it in the locked position. The hammer is skeletonized, so I stick a small pen in and I am able to nudge it down a bit and hear the sear engage the hammer with a click. It seems some additional refinements are in order hear. What am I looking for?

[niemi24s]

It looks as though the hammer is not getting fully cocked by the slide. Keep in mind also that it is an AA conversion kit on top, not a regular .45 slide.
Good troubleshooting, Stefanosg. Now that you've found the problem all that remains is to figure out whether it's caused by the hammer or the conversion kit.

Could be both too, I suppose. There's a blueprint of the hammer in our Tech Issues sections which may help. And, for a USGI M1911A1, the distance between the disconnector rail and the top of the slide works out to 0.008 ± 0.007 inch.

[stefanosg]

Update. I decided to lighten the hammer spring up a bit. I clipped about 3/4 of a loop from the top. The trigger pull has gotten alot better as a result. This still did not fix the other issue. I got my el cheapo Rock Island and tried the slide from it on my build with the same result. I bought the RI originally for the AA kit, and they worked together just fine.

[stefanosg]

Is it possible that the hammer I am using is incorrect? Not high enough to be pushed back by the disconnector rail. Here is the one I am using.

http://www.brownells.com/aspx/NS/store/productdetail.aspx?p=16440&st=965337002&s=36940

[John]

I seriously doubt that the hammer is your problem.

What you are saying is that with the RIA slide on top of that frame you get the same result, i.e. the hammer follows when you release the slide? What if you ease the slide forward? If the hammer doesn't get to the fully cocked position, then it will follow even if you ease the slide forward.

Let us know.

[stefanosg]

Yes, even when I ease the slide forward the hammer follows. I had mentioned earlier that with the slide locked open, I can use a small tool and just nudge the hammer down a bit and I hear it click. Since my last posting, I took the hammer from my RIA and put it on my build. The problem seems to have gone away. I am going to try the other hammer on my RIA and see what happens.

[stefanosg]

I put the build hammer in the RIA and it performs flawlessly. I am looking at the sear spring now and have noticed the the one from the RIA is alot curvier than the build spring. I am going to swap the hammers back and try swapping that part next.

[stefanosg]

Swapping sear springs did not help.

[Joshua M. Smith]

Almost sounds like you have an overlong sear or hammer hooks...

Josh <><

[John]

Stop interchanging parts, you got us confused.

Have you noticed if this problem occurs when shooting? Remember that the hammer is really pounded by the recoiling slide. If it happens only when you rack the slide by hand, even though it is not normal, I am not sure it will happen when firing.

In any case, remove the thumb safety from your pistol and insert it from the right side of the frame, so that it keeps the grip safety in place. Better yet, remove the grip safety too. Now you can see inside the pistol (from the opening of the thumb safety and the opening at the rear of the frame, and see what's going on.

[stefanosg]

Stop interchanging parts, you got us confused.

Sorry about that. I exchanged hammers between the two and they both worked in the opposite pistol just fine. I also tried the sear spring from the RIA in the build pistol. That did not help. I did not try the build sear spring in the RIA though.

I did leave off the grip safety and watched what was going on and everything seems normal, at least from my perspective. Actually I left the grip safety off the RIA as well and watched them both side by side and did not see anything out of the ordinary. I won't get a chance to shoot it till tomorrow afternoon. I was thinking the same thing too as far as the recoil being enough to set the hammer. Is it possible that the edges on the hammer, being new, are not worn in enough to allow the sear to drop in cleanly?

[shovelwrench]

I would advise against shooting it that way.

Take a pic of the trigger group through the grip safety hole(GS removed), and post it for us.

[Joshua M. Smith]

Know what? Humor me for a sec... this is a long shot.

Put all the parts back in except for the thumb safety. Try cocking the hammer with the slide now.

Josh <><

[stefanosg]

Know what? Humor me for a sec... this is a long shot.

Put all the parts back in except for the thumb safety. Try cocking the hammer with the slide now.

Josh <><

I thought I tried that, but I tried it again. No success.

Here are some pics. I linked them to preserve the sizes.

http://www.k-a.net/forum/19111.jpg

http://www.k-a.net/forum/19112.jpg

[Joshua M. Smith]

Press down on the disconnector from the top while watching the sear. What does the sear do?

[stefanosg]

Press down on the disconnector from the top while watching the sear. What does the sear do?

Sorry, I'll have to try it later. My wife wanted to get going and I am no longer home. I'll give it a go tonight. Is there something I should be looking for?

[Joshua M. Smith]

Yep, make sure the disconnector fully disengages.

Josh <><

[stefanosg]

Yep, make sure the disconnector fully disengages.

Josh <><

I've stared at that STI animation and it looks like mine is doing the same thing. What do I look at to indicate that the disconnector has fully disengaged?

[Joshua M. Smith]

#1, the disconnector, will not move #2, the sear, when the disconnector is pressed down from the top (where the slide would usually press on it in recoil.) Or, it shouldn't.

It'll move a bit since you don't have the overtravel stop, also known as the grip safety, installed - IF you do not have an overtravel stop in the trigger itself. (Which, improperly adjusted, could cause the problem you're describing btw...)

http://i19.photobucket.com/albums/b191/WabashShootist/searanddisconnector.jpg
When the disconnector is disengaged, faces #1 and #2 should sit nearly flush.

Josh <><

[stefanosg]

The disconnector seems to be behaving as you described. My trigger does not have an overtravel adjustment screw.

[Joshua M. Smith]

What grip safety are you using?

[stefanosg]

http://www.brownells.com/aspx/NS/store/productdetail.aspx?p=16464&st=965-429-101&s=37012

I noticed in the specs of this grip safety that it is for Commander or Bobbed style hammers. Since I don't have it installed at the moment, could this be the issue?

[John]

You got us all puzzled now. That's not a hammer, that's a grip safety. That's the grip safety you have installed? If so, it should work fine with the hammer you showed us before. That safety won't work with the RIA hammer (if it is a spur hammer).

[stefanosg]

Sorry John I had hammer on the brain, still on my first cup of coffee. Joshua was asking about the GS I had installed. When I linked the part number I noted that it was for certain types of hammers.

Anyway, I seemed to have fixed the problem. I used a polishing stone and I hand polished down the sear. It took about 10 tries before it would work, but now the hammer stays cocked when the slide is drawn. I did perform a number of safety checks to ensure that the sear was firmly engaged. It just seemed to me that the sear was too long for the hammer I was using. I am not certain this was the best thing to do, but the results so far are good. Some time at the range today will help also.

http://www.k-a.net/forum/my1911bld1.jpg

[niemi24s]

Don't forget to do the first test firings with just one round in the mag, then 2, etc. No sense being the talk of the range if the gun goes full auto with a full mag!

[John]

I've never heard a .22 LR full-auto, that should be fun.

[stefanosg]

Don't forget to do the first test firings with just one round in the mag, then 2, etc. No sense being the talk of the range if the gun goes full auto with a full mag!

Thanks I had not thought of that. Sounds like sage advice though. Will do.

[Joshua M. Smith]

So it came down to the sear being too long...?

[niemi24s]

I've never heard a .22 LR full-auto, that should be fun.
Oops! Forgot about the conversion kit. Not as much "fun" as with 45ACP, however. [A little humor there - precious little!] :D

[niemi24s]

I used a polishing stone and I hand polished down the sear. It took about 10 tries before it would work, but now the hammer stays cocked when the slide is drawn.
While your "shortening" of the sear may have allowed the hammer to get cocked, the real problem may possibly be elsewhere.

A mid-spec M1911A1 sear will measure 0.347 to 0.348 inch from the nose to the closest edge of the pin hole.

What does your sear measure?

[stefanosg]

While your "shortening" of the sear may have allowed the hammer to get cocked, the real problem may possibly be elsewhere.

A mid-spec M1911A1 sear will measure 0.347 to 0.348 inch from the nose to the closest edge of the pin hole.

What does your sear measure?

I'll strip it down in a bit to get that measurement. In the meantime, I fired 200 rounds through it at the range without incident.

[stefanosg]

I'll strip it down in a bit to get that measurement.

The measurement I get is about .347 to .348 .

[niemi24s]

Sounds like you did indeed have a long sear. Glad you got it fixed.

[stefanosg]

I really can't imagine that I took that much off. It just seemed that all I had to do was put a little downward pressure on the hammer to get the sear to engage. I just figured a little fine tuning was in order. I tell you though, I have spent many an hour getting Lugers to function reliably. This was a great learning experience for me. I think I can now completely strip and reassemble a 1911 in 5min.

Thanks everyone for you time and help. :appld:

[tazman72761]

I had a similar problem and the fix was that the disconnector was not releasing the sear a few strokes with a stone on the top of the disconnector where it engages the sear legs fixed the problem

[stefanosg]

One thing I really learned about building one of these is that they are not as standardized as you might think. I had to grind down the top of the mainspring housing so it would clear the grip safety. I had to adjust the thumb safety as well and then there is the sear I had to stone down a hair. I have not gotten around to it yet, but I still have to open up the trigger area on the frame to install the trigger I want to use.

[Mgonz45]

Always modify the cheaper part !!!!!!!!! Mod the trigger, not the frame. Most 1911 parts are made oversised on purpose so the builder can dress everything in to a nearly seamless fit.

[tazman72761]

I think I got very lucky the only fitting I have had to do on my commander size Essex frame and slide was the disconnector as stated and fitting the frame to slide everything else has been drop in and go. Barrel was from Numrich arms of unknown Mfg. for $75 looked to be of very good quality it only required a few swipes with a Kart file to be good

[niemi24s]

Always modify the cheaper part !!!!!!!!! Mod the trigger, not the frame.
+1 for this - no, make that +10!!

Unless the cuts in the frame are really grossly out of spec. Check against the frame blueprints in our Tech Issues section to find out. And even if the frame's out of spec - think twice before whacking on it.

Always consider the consequences of botching something.

Given the choice of botching a trigger or a frame methinks I'd pick the . . . well, you get the point huh? ;)

Cheers