The M1911 Pistols Organization Forums Site - Checkmate 7-rounder, case still jumping extractor

AdventureWolf

16th May 2009, 04:59

Guys,

I've got an RIA GI that I've put a few hundred rounds down. It has been far from perfect, but an interesting learning experience.

I've run into a consistent problem - when the pistol is fired and a new round is being fed, the bullet case rim has been jumping ahead of the extractor, causing a FTRB situation.

I've read up on most of the tech threads, including the one most likely related to this issue, regarding magazines.

Based on the opinions of many more experienced forum members, I ordered 2 Checkmate stainless 7-round hybrid lipped dimpled follower mags. Both of these mags, in addition to the stock ACT mag, have experienced the same case rim jump issue.

Here is what I don't understand...after reading all the technical information about magazine design, supposedly the dimple on the follower is some extra insurance just in case the magazine springs start to get tired. Yet, here I am with a brand new magazine with brand new springs and a dimple, and it is still failing.

This brings up a few questions: What is the standard spring strength in these new magazines? I've heard that Tuner suggests using 11 lb springs. If that is the most reliable solution, why don't these magazines just come with 11 lb springs in the first place? Why do some pistols (even from the same manufacturer) function perfectly fine right out of the box, weak springs, no dimples and all, and some seem to need all the help they can get just to run right?

The fact that this has been a recurring issue, does it mean that something internally with the pistol is at fault? If so, what should I be looking for?

John

16th May 2009, 08:04

I would like to see a picture of your gun (looking down the ejection port) to better understand what your jam is.

RickB

16th May 2009, 13:58

G

This brings up a few questions: What is the standard spring strength in these new magazines? I've heard that Tuner suggests using 11 lb springs. If that is the most reliable solution, why don't these magazines just come with 11 lb springs in the first place? Why do some pistols (even from the same manufacturer) function perfectly fine right out of the box, weak springs, no dimples and all, and some seem to need all the help they can get just to run right?

There's a thread, on this forum I think, started by a guy who solved his function problems by removing the 11# springs and going back to the stock ones.
What about your other springs? Stock? Do you know the ratings?

Hammerdown

16th May 2009, 14:11

Is this on any particular round (first, last), or is it on every round?

There was a thread with another member having this same issue, and Tuner mentioned something about certain brands of ammo having a slightly undersized case rim that could cause them to jump the extractor. I think it was Blazer. What type of ammo are you using?

log man

16th May 2009, 14:20

First round, last round, don't know, but since you mention the dimple, that would be effective on the last round only. New springs are mentioned because weak ones allow the cartridge to come out more easily. When a new mag does this I immediately think that the mag wasn't cleaned first, no oil or lubrication of any kind should be in the mag as that will aid in a premature exit from the mag by inertia forces at the moment of recoil.

LOG

AdventureWolf

18th May 2009, 01:51

John,

I can't take a picture now, but if I was to re-create the situation, the slide would be about 1/4" to 1/8" rearward, a cartridge in the pipe, with the extractor claw resting against the bottom of the case head, behind the cartridge.

So far, the extractor hasn't jumped the rim any time this has happened (from what I know), just creates the FRTB situation.

This case rim jump failure has happened with both types of magazines (stock Novak mag and both new Checkmate mags)

The last few times this failure has happened, it was on the last round in the magazine, but for the first few times it happened, it was not on just the last round.

Ammo used was Winchester White Box and Blazer Brass. Failures occurred with both.

Now I'll admit, I did not clean out the mags before shooting, but I took one apart last night to examine it and did not notice any oil or anything else that would impair function.

Right now, I don't know what the stock spring # is in the magazines, but some of the research I've done here indicates that moving up to an 11# spring could help solve this problem.

Why do some 1911s function just fine with old worn out, low powered springs, and others need really high tension springs? I'm still new to this 1911 thing so your patience is appreciated. Thanks guys.

John

18th May 2009, 06:49

If the claw of the extractor is above the rim of the feeding round, in other words the rim of the round hasn't quite slipped under the claw, then your extractor tension may be a little high. Try this to understand what I am talking about. After you load a round in the pistol (chamber it) pull the slide back a little and watch the area where the claw of the extractor has "embraced" the rim. If when the jam occurs, the rim hasn't slipped under the extractor claw, you may need to reduce the extractor tension a little. There is an article on that in our Technical Issues forum.

But if the rim of the feeding round is in front of the extractor claw (not touching the breech face) then it's a whole other issue all together, you need to check your magazine spring first.

niemi24s

18th May 2009, 11:29

Also make sure the extractor claw/hook has the proper radius at its bottom, shown as area G here: http://i129.photobucket.com/albums/p232/niemi24s/P078290001e.jpg

1911Tuner

18th May 2009, 11:48

So many zebras stirring up dust. Let's start with a horse.

What recoil spring do you have in the gun?

AdventureWolf

18th May 2009, 21:01

John:
I can visualize what you are talking about. Actually, the pistol had several 3 point FTRBs that, in my limited knowledge, were caused by a too-strong extractor. When I had the slide off the pistol, and would try to slide a rim under the claw, it took a LOT of pressure to do so. Likewise, on every jam, I remember that the rim never quite made it under the extractor claw. I retensioned the extractor based on the link I got from these forums (and, not really knowing what I was doing!) and the tension is definitely less now, and what do you know, those 3-pt failures disappeared!

The issue going on now is the latter that you had mentioned, which is that the case rim never contacts the breech face, as it slips up past the front of the extractor claw.

Tuner:

You know, I have no idea about the recoil spring! It is the stock spring, so I'd imagine 16-17lbs? If there is a way to test this I will try it. I know that some people recommend a higher ## spring like an 18lb or higher, but based on the posts I've seen here, the optimal balance (or at least ideal) seems to be 16lb recoil and 23lb mainspring. I've also read your posts about the last round losing control and when the breech face hits the rim, it can actually knock it forward, losing contact with the breechface and thereby slipping ever so slightly in front of the extractor claw. For what its worth, the breechface on this pistol is somewhat rough. I've tested the pistol with the recoil spring removed while chambering rounds, and even if it a smooth motion, if I go slow enough, the feed lips let the round loose and it pops in front of the extractor. With the pistol properly assembled, I cannot remember a time when releasing the slide at normal speed ever caused this situation. This information leads me to believe the magazines are at fault, per your discussion. However, I'm perhaps a little natually inquisitive or skeptical about just how a 10lb or 11lb spring would fix the entire issue, especially since the magazine is new, with a new spring. It brings to mind what I've heard in your posts before - just because its working, doesn't mean its working right. Throwing a higher ## spring in the mag may very well cure this FTRB, but am I just covering up a deeper issue when other pistols can run these magazines completely stock without a hitch? Does this also mean that my particular pistol is going to be a little hyper-sensitive to magazines, that as soon as that 11lb spring starts getting tired, bam! More malfunctions? The most frustrating part is not the actual malfunction, but more of not exactly knowing what is happening, or even moreso, why it is happening in this case and why even with these highly recommended magazines, the problem still exists. One of my original questions still remains - if this is a widespread problem with the magazines, why are manufacurers still using inadequate springs?

Thank you all again for your wisdom and experience.

AdventureWolf

21st May 2009, 21:11

Any thoughts?

1911Tuner

21st May 2009, 21:49

Any thoughts?

How about exactly what is causing it?

The tapered lips allow the rear of the cartridge to rise as the round feeds. If the mag tube isn't properly tempered, the lips spread farther apart, and let the rim rise above the dimple. When the slide smacks the impact abutment, the frame jerks rearward while the round stands still...literally pulling the gun out from under the cartridge as though the dimple was missing. When the slide returns to battery, the cartridge is no longer controlled...and the slide pushes it into the chamber ahead of the extractor instead of the magazine pushing the rim under it.

Measure the width of the magazine at the top with the mag empty. .530-.535 inch is what you want. Much more than that, and it causes the issue that you're having.

Load 3 rounds and measure it again. The width should close up. Lightly squeeze the mag in a vise with the follower and spring removed. LIGHTLY. When you've got the width within those limits...reassemble and see if it opens back up. If it doesn't, it's probably cured. Then check to see if the mag will drop free from the gun. If so, you're golden. If not...send it back. You got one of the earlier magazines that caused Check Mate to retool and change their specs.

Luck to ya, m'fren.

Icepick15

22nd May 2009, 00:44

Check Mate changed their specs? Marvelous.

In the "infamous group buy", I got 50 Check Mate magazines...some blue, some stainless. All seven round hybrid feed lips and dimpled follower. I have some that allow the last round to jump the feed lips. Also, some that don't lock the slide back on empty. And I haven't even tested all of them yet.

I didn't need 50 magazines. Some of the guys at work wanted some, so I paid for them with the intention of the guys paying me back for their magazines when they arrived. When I started testing, and found the problems, I couldn't in good conscience let them pay me for what might be faulty magazines. So I kept all the magazines and ate the loss. I have just enough that have been proven reliable for carry, and the ones that failed are living in my range bag.

Now what? I didn't know Check Mate identified a problem and changed their specs. I wonder if they'll replace the magazines? Problem is, I haven't tested all of them. And with the ammo situation being what it is, I don't think I could get my hands on enough 45ACP to test all of them to my satisfaction...not to mention the cost factor.

As Chester A. Riley was fond of saying......what a revolting development.

AdventureWolf

22nd May 2009, 02:12

Thanks for the input...so in just about any case, this can be attributed to magazines? Is there any case where this would be more a problem with the pistol?

I'm actually comparing the thickness of the stock ACT mag and the Checkmate. The Checkmate is just a tiny bit under a 1/16" thinner than the ACT - although I will need to get a caliper to get an accurate measure.

1911Tuner

22nd May 2009, 09:52

Is there any case where this would be more a problem with the pistol?

I've seen it happen more with pistols that are oversprung, especially when used with undimpled followers and soft springs.

Icepick...Check Mate altered their specs due to magazines not dropping free. Reports of last round push-feeds have been trickling in, but aren't all that common. Adolphuscusins...the young fella that I worked with recently...had 4 that did it. I was able to fix that problem by squeezing the tubes a little, but 3 out of the 4 wouldn't drop. I advised him to send'em back. Check Mate will make it right. In respect to their warranty and customer service, they've been like Sears and Craftsman tools.

I ordered 65 of the early Hybrid 7-rounders separate from the group buy...all carbon steel. I replaced the springs with Wolff 11-pound units...and all have been flawless. Sometimes these things happen.

John

22nd May 2009, 10:01

I ordered 65 of the early Hybrid 7-rounders separate from the group buy...all carbon steel.

Man, when you buy things, you buy wholesale, that's for sure!!!!

texagun

22nd May 2009, 10:29

I ordered 65 of the early Hybrid 7-rounders separate from the group buy...all carbon steel. I replaced the springs with Wolff 11-pound units...and all have been flawless. Sometimes these things happen.

Any idea what kind of springs the Checkmates come with? Just wondering if they are vastly different from the 11# springs from Wolff?

1911Tuner

22nd May 2009, 11:04

Man, when you buy things, you buy wholesale, that's for sure!!!!

Yup. I don't play. I quit school 'cause they made me take recess...

Any idea what kind of springs the Checkmates come with? Just wondering if they are vastly different from the 11# springs from Wolff?

Good question. The ones that came in mine were good, but the tension was a little lighter than the Wolff springs. My guess is around 9.5 pounds...which is GI spec. I like the 11-pounders because they hold tension at about 10% above GI spec after taking a set...and stay there for many thousands of rounds.

To put it in perspective...I've got 72 range magazines...all 7-round Metalform wadcutter mags that I've been using hard for nearly 10 years. After I bought'em, I installed Wolff springs. Metalform's 7-round springs leave a lot to be desired, though their tubes are top-notch. 10 years...and I'd be afraid to guess how many hundreds of thousands of rounds later...the springs are still stronger than new GI-spec springs, and the magazines perform perfectly. I had to replace the follower on one about a month ago due to jumping the slidestop lug. I replaced it with a Check Mate follower.

Of the 65 Check mate "hybrid" mags that I bought...I sold 25 of'em to various guys who needed a couple good magazines. 2 here and three there. A few I gave away. I asked for feedback, and have had zero complaints. Of the ones that I kept...I ran'em all hard for about 3 months...and there have been no failures in any of over a dozen of my guns, an about that many more that belonged to other people. They even ran flawlessly in guns that choked on other OEM equipment and aftermarket mags...which sorta mystified the owners...but was no surprise. I've often found that the tapered/timed hybrid feed lips cure feed problems in many guns. Not all...but too many to discount.

The OEM springs that I removed have been given away to people who needed new mag springs, and I've had no complaints...but not many guys punish magazines with the high round count that I do.

Conclusion:

Check Mate's OEM 7-round springs are completely adequate for normal use, but lose tension when a shooter really puts'em to the torture test. They seem to be good for about a hundred cycles before problems start showing up. 7 hundred rounds was...and is...probably about the life of GI spec mag springs. In all fairness, the US military viewed magazines as expendable, never intending for one magazine to be used for a 10,000 rounds. That's why they contracted for millions of'em, like replacement parts for the pistols. They could have opted for higher quality springs that would have cost maybe 2 cents more at the time...but 2 cents per unit for 2 million springs adds up.

Metalform offers an upgrade to Wolff springs in their stainless mags for an extra buck-fifty or so...or at least that's what it cost a few years back. That was a throwdown bargain, and still would be, even at 3 dollars extra.

When we talk gunsprings...think Wolff. They've been making gunsprings and nothing but gunsprings for decades. They've got a handle on it. Like that Gerber baby food slogan.

"It's our business. Our only business."

AdventureWolf

23rd May 2009, 17:14

Conclusion:

Check Mate's OEM 7-round springs are completely adequate for normal use, but lose tension when a shooter really puts'em to the torture test. They seem to be good for about a hundred cycles before problems start showing up. 7 hundred rounds was...and is...probably about the life of GI spec mag springs.

...which is again the part that mystifies me. On one hand, these magazines are just fine, but on the other they are not?, since it seems that the spring is just weak enough to cause that last round to jump around and pop in front of the extractor. This is within the first hundred rounds of the magazines life, so I don't think it could be a 'worn out' type issue.

Tuner, I think I'm going to take your advice :D and get myself some 11# springs for the mags, although I'm still baffled that magazines with springs which are considered adequate have shown from limited experience to not be, which has been why I wondered if something was up with this particular pistol. Do magazines need any kind of break-in?

I suppose when I'll try the 11#ers, if they work, I'll have to just shut up about this whole thing :D I just want to know why in this pistol OEM chokes. Ahh my introduction to the 1911. Lots to learn lol.

niemi24s

23rd May 2009, 17:50

{[When referring to CheckMate magazine sporings]} The ones that came in mine were good, but the tension was a little lighter than the Wolff springs. My guess is around 9.5 pounds...which is GI spec.FWIW, I just tested the springs in three CM 7 round mags: a made-for-Colt hybrid lip and two GI tapered lip, late release models. These mags are about a year old and have seen little use.

The forces holding the 7th round up against the feed lips were 8.8, 7.7 and 7.1 lbs, respectively. When a Wolff 11 lb spring was installed in the Colt/CM mag, the force measured 10.7lbs.

The forces posted above are averages of several readings and have a variation of as much as ± 0.4 pounds.

Regards

John

23rd May 2009, 18:29

The mags we got for you guys during the last group buy had the extra strength springs in them. Did someone measure the force, like Niemi did? We all need to know.

niemi24s

23rd May 2009, 22:01

Just in case it matters, the Colt/Checkmate hybrid lip magazine was shipped from Brownells during April, 2007. The other two were shipped from Checkmate during October, 2008.

Regards

bradp

30th May 2009, 14:21

I can measure the force at my lab (work).. but I need to know how. How far down should I press the follower when I take a reading on the force of the spring?

Brad

niemi24s

30th May 2009, 16:36

How far down should I press the follower when I take a reading on the force of the spring?I've never really been able to figure that out in order to depress the follower to it's fully loaded level and thus compress the spring to its "fully loaded" length. Too many angles and variables - like the follower's position.

Wolff says their spring ratings are determined at the "magazine fully loaded length", so what I finally did was just let a full load of cartridges determine the length to compress the spring. For a 7 round magazine I load 6 rounds and then add an empty case as the 7th "round". The empty case has a hole drilled through one side close to the bottom to allow the insertion of my tester's push rod. The tip of the pushrod's at the bottom of case for stability.

A thin (I used 0.0015") strip of steel shim stock is folded and inserted between the case rim and both feed lips to sense (by its looseness) when the tester's pushrod has pushed the case down just a teeny bit from the lips. Looks like this: http://i129.photobucket.com/albums/p232/niemi24s/P095300001b.jpg After taking a series of force measurements I then find their average value and add the weight of those test items acting (because of gravity) downward on the follower (cartridges, "holey" test case and pushrod - because my tester is vertical).

Don't know what kind of fixture Wolff uses to test their springs. There may be better ways than this to test them, but it's what I came up with.

Regards

bradp

30th May 2009, 18:39

Nice, I like it.

I whipped up a similar jig at work.. but my balance/scale has a 3100 gram maximum, not enough to measure up to 11lbs. I'll look around some of the other laboratories tomorrow, see if anyone has a beefier scale.

Will try again tomorrow.
Brad

AdventureWolf

2nd June 2009, 00:31

Find anything out about those spring weights?

bradp

2nd June 2009, 10:58

I need to find a different balance at work.. I'll scour the labs today.

niemi24s

2nd June 2009, 11:26

If you can't find a suitable balance or scale at work, there's always the checkout counter scale at the grocery store or the Post Office's scale. They usually go up to at least 25 pounds and are quite accurate - plenty accurate for what you're trying to do.

Measuring forces on compression springs when squeezed to a certain length is hardly precise. If you take 6 separate readings chances are slim that two will be the same even if you measure, say, 10 pounds to only the nearest ounce. And you'll probably be astonished at the difference between the highest and lowest measurements.

bradp

2nd June 2009, 13:23

I can see the look on the post office worker's faces when I walk in with a few dozen loaded 1911 magazines. :)

1911Art

7th June 2009, 23:18

AdventureWolf

9th June 2009, 01:30

My bullseye gun is also "jumping the extractor" with Checkmate mags. The gun is 100% with PowerMags or 47Ds for more thousands of rounds than I can remember. Two of the four blue steel, 7 round mags have the problem. It's the first round - the round is pushed cockeyed into the chamber ahead of the extractor.
I got 4 in the last group buy since these were the mags that work when others won't. Bummer.

I wonder if these mags have the standard springs and not the more powerful springs? I'd like to give the checkmate mags I have more of a chance, but ammo for this thing is really expensive right now!

Lazarus

10th June 2009, 11:16

Measure the width of the magazine at the top with the mag empty. .530-.535 inch is what you want. Much more than that, and it causes the issue that you're having.

Load 3 rounds and measure it again. The width should close up. Lightly squeeze the mag in a vise with the follower and spring removed. LIGHTLY. When you've got the width within those limits...reassemble and see if it opens back up. If it doesn't, it's probably cured. Then check to see if the mag will drop free from the gun. If so, you're golden. If not...send it back. You got one of the earlier magazines that caused Check Mate to retool and change their specs.

Pardon my ignorance, Tuner, but I need to ask where to expect the .530-.535 inch measurement? Does this apply only to USGI mags or to hybrids as well? My checkmate USGI style mags all came from the Ty Eng fiasco, which were probably produced early in the development cycle. The only place I can come close to .535 is at the very tip of the feed lips opposite the location of the dimple on the follower.

Lazarus

Lazarus

18th June 2009, 17:26

Seems that this thread turned into a discussion of magazine springs, but I found the mention of magazine feed lips to be most interesting. I'm especially interested in whether my mags are set to release too early and I'm assuming that the width measurement must be taken somewhere in the middle of the feedlip (adjacent to the dimple in the follower?) where the round would normally release. A magazine that releases too early would not fix itself with a stronger spring, even though mag springs are an important consideration overall.

I'd especially like to check the mags dimensions before squeezing them in a vice, or before contacting Checkmate. Up until now, I have been concentrating on getting the barrels to have the proper setback, the frame bed the correct height, and the frame ramp to have the right angle. So far, I have had an occasional next to last round jam that might be caused by the early release syndrome.

Thanks!
Lazarus

1911Tuner

18th June 2009, 18:29

Seems that this thread turned into a discussion of magazine springs,

Well...it's tough to analyze this type of malfunction without including the spring...because that's what causes it about 99% of the time.

So far, I have had an occasional next to last round jam that might be caused by the early release syndrome.

The release point is fixed. Whether it's an early or late release type depends completely on where the flare is located. The malfunction herein described is technically referred to as "Jumping the Follower" and is caused by the cartridge rim
lacking a mechanical means to limit its forward travel. The dimple plays a role. The spring plays a role. In the case of the malfunctioning hybrid magazines...it's caused by the taper of the lips allowing the rim to ride over the dimple.

The tapered lips allow the rear of the cartriege to move up as it moves forward. This is a critical factor in its inhrent feed reliability...but if the taper is wrong or if the lips spread due to incirrect heat-treatment...the round moves up too far, and the rim skids over the dimple...which has the same effect as it not being there. Then, when the slide smacks the frame's mpact abutment...the pistol is litereally jerked out from under the round. The cartridge is now loose. The result is either the slide locking with the round lying loose on top of the lips, or...on the other end of the spectrum...a push-feed occurs in which the cartridge is chambered ahead of the extractor. At that point, the gun will either suffer an out of battery failure...or it will snap the extractor claw over the rim, and function as if all is well...until the extractor claw breaks off.

The latter situation is the most common, and has contributed to the myth that the 1911's extractor requires frequent tuning and retensioning. The first indication that something is amiss is an extractor that loses tension quickly. Eventually, it will fail if this push/snapover feed is allowed to continue. It's not a matter of if...but when.

niemi24s

18th June 2009, 20:27

Hi Lazarus:I'm especially interested in whether my mags are set to release too early and I'm assuming that the width measurement must be taken somewhere in the middle of the feedlip (adjacent to the dimple in the follower?) where the round would normally release.I recall a few weeks ago we exchanged some PM's about this in which you'd given me dimensions for a Go and a No-Go gauge for checking the release point.

I remember the No-Go gauge was 0.475" OD, just like a case rim, and when placed just at the rear of the follower dimple the feed lips should retain the gauge.

The Go gauge had a smaller OD and when put in the same location the lips should not retain this gauge.

Unfortunately, I deleted the PM with the Go gauge's OD. Was it 0.465"?

Cheers

P.S.: I use this fixture to measure the release point:
http://i129.photobucket.com/albums/p232/niemi24s/P08B030004c.jpg It'll tell me how far a cartridge moves before the lips release it (to within about 0.004"n or 0.005") but I never knew when the lips were supposed to release it until you mentioned those gauges.

niemi24s

18th June 2009, 20:52

Hi Tuner:

I'm having a hard time understanding this:. . .The tapered lips allow the rear of the cartriege to move up as it moves forward. [deleted]...but if the taper is wrong or if the lips spread due to incirrect heat-treatment...the round moves up too far, and the rim skids over the dimple...If the round moves up too far, it is being moved up (too far) by the follower - and its dimple.

How is it possible for the cartridge to get away from the follower & dimple - unless maybe the spring's force can't accelerate the follower fast enough to keep up with the faster rising cartridge? :confused:

Cheers

1911Tuner

19th June 2009, 08:18

How is it possible for the cartridge to get away from the follower & dimple

With the tapered lips, as the round moves forward, it also moves up. If the taper is too wide...or the dimple a little short...the rim skids across the top of the dimple instead of being halted by it. If it exits the magazine, the slide locks to the rear. If it doesn't, and the rim sits on top of the dimple or just forward of it...the round push-feeds into the chamber ahead of the extractor. Normally, timed release magazines allow the cartrige to jump the follower if it gets completely pastthe dimple. If it push-feeds...the rim is sitting on top of the dimple. Halted...but just barely. All the slide has to do is touch it to send it out of control.

Like the firing pin stop, mainspring, and recoil spring...it's a system. The feed lips...the amount of taper and and their release point. The spring tension. The size and location of the dimple. All must be in spec for the system to work correctly. If all is well, the feed reliability of the pistol is second to none. If one part of the system is wrong, the whole system is compromised.
Incidentally, the GO/NO-GO release gauges only apply to full tapered GI "Hardball" feed lips. If the magazine has a timed release point, it will release a rim size much larger than .475 inch.

I use a .473 gauge for hardball magazines. With the rim forward of the dimple, touching the front of it...the gauge must release under spring tension only, with light drag. I've developed a "feel" for the amount of drag, and don't need to use a NO-GO gauge to adjust hardball feed lips.

Lazarus

19th June 2009, 15:17

Thanks for the clarification, Tuner.
-Lazarus

niemi24s

19th June 2009, 20:26

Hi Tuner:

Thanks for the additional explanation, and also for this: Incidentally, the GO/NO-GO release gauges only apply to full tapered GI "Hardball" feed lips.Just happen to have two unused Checkmates like this. I figured just using a case with the rim turned down to 0.473" would do the trick.

Cheers

1911Tuner

19th June 2009, 21:21

I figured just using a case with the rim turned down to 0.473" would do the trick.

That'll work once...maybe twice...but the brass case rim won't hold up to repeated gauging. I whipped one up years ago from 1018 steel and it's holding up nicely. I rarely have occasion to use it any more, but did so recently for a couple of GI magazines that 1944Colt sent to me to tweak.
Reports were good.

niemi24s

19th June 2009, 21:41

That'll work once...maybe twice...but the brass case rim won't hold up to repeated gauging. I whipped one up years ago from 1018 steel and it's holding up nicely.Thanx for the tip. Not sure how much use I'd give it, but I may as well make it to last.

Cheers

niemi24s

3rd July 2009, 23:57

FWIW, here's a version of the 0.473" dia. gauge mentioned by Tuner for use in checking magazines with the original long, tapered, late-release GI lips: http://i129.photobucket.com/albums/p232/niemi24s/P097030003d.jpg Lazarus provided the gauge to check the only two magazines like this I have.

One released the gauge when it was 0.06" ahead of the dimple, the other at 0.16". Both mags had the original springs, and neither has been used - so I don't even know how well they work!

Regards

Lazarus

4th July 2009, 19:17

I hope I am taking the measurement at the correct place, namely where the feed lips stop tapering outward and become parallel??

http://www.eskimo.com/~parkerc/blued.jpg

or here:

http://www.eskimo.com/~parkerc/stainless.jpg

I have a dozen Checkmates, all ordered early in the production cycle. Here are the measurements:
Stainless: .543, .543, .541, .547, .543, .540
Blued: .540, .541, .545, .544, .548, .540

Do all of these magazines have to go back to Checkmate for exchange? As is noted in a recent post, the dimples on the stainless followers are too shallow also. I've emailed Checkmate twice, but no response.

Lazarus

1911Tuner

4th July 2009, 20:43

Lazarus...Place the flat portion of the caliper jaws on the sides of the magazine...as though it were a wrench...grasping the whole magazine. Line it up with the top of the magazine, with the top of the jaws flush with the top of the lips. Get the curved front of the magazine get deep enough into the caliper jaws to touch the scale...and use it as a stop...so that your measurements will be consistent.

.535-.540 is about what you're looking for.

Dan...The gauge should release by spring pressure with a slight drag with the rear of the gauge touching the front surface of the dimple. Yours are releasing late.

I tweaked the lips on a few mags for 1944Colt last year sometime. He reports that they're behaving nicely.

Lazarus

4th July 2009, 21:38

Thanks, Tuner. Measurements taken per your description yield even larger numbers than I originally posted. I'm going to assume that these mags must all be early production, so I will call Checkmate for an RMA.

Lazarus

1911Tuner

4th July 2009, 22:14

Put one round in the mag and measure again. If it comes down to within spec, you can probably fure your problem by punching that dimple a bit deeper. Easy does it. If you make it stand too proud, it'll hang the last round up during the feed.

niemi24s

5th July 2009, 12:46

Made some "edge finders" to hold the caliper jaws repeatably flush to the top surface of the feed lips (as I think Tuner described in Post #44)... http://i129.photobucket.com/albums/p232/niemi24s/P097050002b.jpg...and took some measurements of the two mags I've got with the GI lips:

• As in the pic (empty): .... 0.535" & 0.528"
• Follower pinned down: .... 0.531" & 0.525"
• 1 Rd in mag: ................. 0.536" & 0.528"
• 3 Rds in mag:................ 0.533" & 0.525"
• 5 Rds in mag: ............... 0.530" & 0.524"
• 7 Rds in mag: ................0.531" & 0.525"

Because of the relatively thin caliper jaws (0.116") they do not get down to the wider portion of the mag body's aft surface so these measurements are of the mag tube width just forward and slightly below the front of the lips.

I then tested each of these mags for the release point with the 0.480" Dia. gauge mentioned on page 180 of Kuhnhausen's Vol II (which says Ordnance specs required this gauge be released within a distance of 0.820" measured parallel to the lips) & got 0.681" & 0.732".

Dimple heights on both are within the 0.012 ± 0.003 inch derived spec, so as far as I can tell both of these magazines (Checkmate CM45-7-B-GI) are within the specs for a hybrid lip magazine. I've never seen a blueprint for a GI lip magazine, so don't know what (other than the lips) might be spec'd different.

Regards

Lazarus

5th July 2009, 19:45

Tuner, thanks for all the added info. I keep coming up with way over .530-.535" no matter which way it is measured. Guess that tells me things are not right with the feed lips. I measured the tops of the magazines as per Dan's photo:

http://www.eskimo.com/~parkerc/parallel.jpg

Most of my mags are showing .547-.550" like this one:

http://www.eskimo.com/~parkerc/widetop.jpg

Also, neither the stainless, nor the blued mags will hold the GO gauge at the proper placement without popping out of the magazine. Another indication that the lips are too wide. The change with a round inserted in the magazine is on the order of .001 to .002 thousandths.

Lazarus

1911Tuner

5th July 2009, 20:34

Laz...Punch the dimple a little deeper. Just by the photos, the lips look like they'd release a little early. The beauty of GI/Hardball type lips is that they're tuneable to a certain degree.

niemi24s

6th July 2009, 13:08

Most of my mags are showing .547-.550". . .If your blued steel Checkmate magazines behave like mine, their tube widths just ahead of the lips should decrease about 0.003 to 0.004 inch with the follower removed or pinned down away from the lips [See top two lines of data in Post #47].

If yours do, your tube widths should decrease to maybe 0.543/0.544 to 0.546/0.547 inch and be within the Ordnance spec of 0.535 to 0.549 for just the tube (no spring or follower). Maybe it's just the dimple height, as Tuner suggested, or the lip geometry. Or poor heat treatment.

Cheers

toolman

6th July 2009, 16:02

So many zebras stirring up dust. Let's start with a horse.

What recoil spring do you have in the gun?

Hey Guys, don't forget about this one. The last time I had this problem this is what was causing it. My recoil spring was very old and weak.

It wouldn't hurt to check the recoil spring.

Lazarus

6th July 2009, 19:29

Toolman,

I'm fairly certain this thread began because the rounds were releasing too early, before the rim was under the extractor. Putting in a heavier spring would make the problem worse, not better, because the rounds would fly forward even faster with a stronger spring.

I spoke with Jackie @ Checkmate today and she graciously offered to bring the feed lips of my mags back into spec, so I sent them in. Can't beat that.

Lazarus

niemi24s

6th July 2009, 23:01

Putting in a heavier spring would make the problem worse, not better, because the rounds would fly forward even faster with a stronger spring. But if the recoil spring was too weak for the ammo being shot, wouldn't the slide would come back too fast, smack the impact abutment too hard, and make it harder for the top (or last) round to stay in the magazine?

toolman

7th July 2009, 09:59

But if the recoil spring was too weak for the ammo being shot, wouldn't the slide would come back too fast, smack the impact abutment too hard, and make it harder for the top (or last) round to stay in the magazine?
This is more along the lines of what I was thinking. The spring could be to weak, after all, 1911's are like cars, you get a bad part every once in a while. If fixing the mags doesn't do the trick you could try replacing the recoil spring with a new 16 lb. recoil spring.

Sniper350

7th July 2009, 17:34

niemi24s

7th July 2009, 22:59

FWIW, here's a pic of the "quick & dirty" 0.480 inch dia. maximum case rim gauge mentioned in Post #47: http://i129.photobucket.com/albums/p232/niemi24s/P097070002a.jpgIt's just a 1/2" washer turned down to 0.480" and super-glued to the head of a case that had its rim turned down to about 0.460".

Regards

Lazarus

8th July 2009, 13:06

Niemi24s ....... this is the Horse Tuner was talking about earlier ! The recoil spring is most likely the problem here. I have an S.A. Ultra Compact 3" which is very hard on that single recoil spring that it uses. If I shoot Hot Factory Hardball - more than 500 rounds, I will need to change the recoil spring or the exact failure the OP was talking about will happen every time ........ the bullet will jump ahead of the extractor.
JF.
Sniper,
By hot factory hardball, do you mean +P ammunition, or standard 230 grain loads? There are other things to consider in your scenario. The Ultra Compact might indeed be punishing to the recoil spring, especially with +P ammo. Still, my thinking on the subject is that your magazine is releasing too early regardless of the perceived slide velocity. What magazine are you using? Have you tried to increase the magazine spring strength as an alternative to changing recoil springs?

As an experiment, I ordered the full range of recoil spring weights to see how the various springs would effect the ejection of brass. I figured that I would see dramatic differences because the slide would be moving more slowly when it smacked the VIS. The results were almost no change in the distance my brass was thrown, no matter how strong or how weak the spring happened to be. Without more scientific testing, I couldn't say how much the slide velocity varied. But, at least from the results of my impromptu experiment, the recoil spring strength does not control the rearward slide velocity as much as people believe. Forward velocity change, however, is a different matter. In your case the weakened recoil spring should result in slower forward velocity and improve controlled feeding, wouldn't you agree?
Perhaps there is another explanation for what you have observed. The stronger spring may be needed to make certain that the extractor jumps the cartridge rim and the slide goes completely into battery? I still believe that the magazine is of primary importance in preventing push feeds and double feeds.

Lazarus

tophatjones

23rd August 2009, 21:28

FWIW, here's a pic of the "quick & dirty" 0.480 inch dia. maximum case rim gauge mentioned in Post #47:

It's just a 1/2" washer turned down to 0.480" and super-glued to the head of a case that had its rim turned down to about 0.460".

Regards

Sorry bout reviving an old thread, but that rim gage is just too awesome! :appld:

Also, what would be wrong with measuring the top of the magazine width by aligning the back of the mag (as opposed to the front curvature) against the scale of the calipers? Seems a bit more precise, at least to me. I get ballpark .533" with current production CMI SS 7rd hybrids.

niemi24s

23rd August 2009, 22:33

. . .what would be wrong with measuring the top of the magazine width by aligning the back of the mag (as opposed to the front curvature) against the scale of the calipers?Nothing, I guess. IIRC, I did it the other way just because it was easier (not as awkward) for me to hold on to the magazine. :p

Regards

AdventureWolf

26th August 2009, 02:24

So, with regard to the original pistol in question:

I put 50 rounds down range (Blazer brass, I like the stuff!) and no failures to return to battery. It *almost* had one when a buddy racked the slide slowly (case rim was directly under extractor claw and as we were looking at it, it snapped in to battery, -- this can't really be attributed to a firing problem though.

One thing I noticed...when I would slowly hand cycle the weapon before, the rounds would 'pop' up from the magazine lips and fly out past the extractor claw. This time, I tried to induce that same thing, no deal. It's like the claw started grabbing the case before the feed lips fully released. Don't ask me whats different this time though :confused: :D

I still need to get some 11# mag springs and check my recoil springs. The pistol, on the 49th round, and last round in that particular mag, fired and then had a failure to lock the slide back (which I thought was somewhat funny, because I had previously experienced some problems with premature slide lock)

I think we are still looking for a consensus on mag spring weights, how accurate they are to their description, and how they compare with OEM springs.

That's my update!

1911Tuner

26th August 2009, 10:56

It *almost* had one when a buddy racked the slide slowly (case rim was directly under extractor claw and as we were looking at it, it snapped in to battery, -- this can't really be attributed to a firing problem though.

That's indicitive of a 3-Point Jam...so it is a firing problem.

Related to this issue, I received two of Hammerdown's worst offending magazines to troubleshoot and test fire.

The magazines were within spec, and the dimple was arresting the bottom cartridge as per design. I opened up the follower angles a little...about a half-degree or so...took'em to the range with 3 different pistols and two different lots of ammo.
230 grain jacketed ball and 200 grain cast SWCs. OAL was 1.260 and 1.245 repectively. Both lots loaded with 6 grains Unique. MV 830 and 875 respectively.

Two early Colt 91A1s and a mid-80s production Springfield 1911A1 were the test platforms. All three are proven reliable performers.

An additional two magazines full of the jacketed ball...which is GI Hardball equivalent...were shot through the Springfield.

Zero malfunctions. Feeding was smooth and positive.

Now to send'em back to him and see if the problem goes away in his pistols.

AdventureWolf

27th August 2009, 02:09

Tuner,

Can you elaborate on what you mean by opening up the follower angle? Would the bullet then be resting in the magazine at a steeper/shallower angle? What was the desired outcome of the modification to that part?

I'll definitely be interested in seeing how Hammerdown's pistol reacts to the mags.

Like I had said, this last time out was much different - before that I'd be getting almost 1 failure (case rim in front of extractor claw) per magazine. However, I don't think things necessarily go away by themselves.

I'd like to know how I can take a look at my own mags, any input is definitely appreciated! :appld:

1911Tuner

27th August 2009, 06:12

Can you elaborate on what you mean by opening up the follower angle?

Surely.

When I removed the followers and compared them to the angle of the magazine...they matched exactly. The followers were closed up a bit too much. I've found that this is the case with most new 7-round magazines...so it seems to be a common mistake.

To open it up, you've gottas be careful not to bow the top or the rear leg. Clamp rear leg in a vise as close to the bend as you can and still leave room for a thin screwdriver blade to reach the bend from the top. Wedge it in and lever upward, being careful to support the top to avoid bowing it.

Check Mate's followers are tough and springy...hardened...so you'll need to sorta "bounce" it and let it spring back...checking it as you go until the bottom of the rear leg just slightly protrudes from alignment with the rear of the magazine tube. About the thickness of the follower will do.

A word of caution on stainless followers. Be VERY careful. They tend to be a bit more brittle than carbon steel, and will snap easily. It's for this very reason that I order carbon steel magazines instead of stainless. Most followers need a little tweak, and carbon followers are much more malleable than stainless.

AdventureWolf

31st August 2009, 01:25

Tuner,

got it. Know exactly what your talking about. Next time I have the pistol out I'll pull the mags apart and see what I find. They are stainless...so I'll have to see about that ;) Thanks for the heads up.

barrow

1st September 2009, 00:17

So a half-degree less than the angle of the magazine is about right?

DSpecial

1st September 2009, 07:15

Don't know if this is a factor, but from experience I had a pistol with a poorly finished extractor that would pull the empty halfway out, apparently the next round in the mag would exert enough pressure to allow the cartridge rim to jump over the extractor lip, the slide would cycle and the slide would force the next round into the empty that was still partway in the chamber and I got a jammed FTRB.

DSpecial

barrow

1st September 2009, 14:10

Oh never mind, I didn't read your last post close enough, tuner. You explained it perfectly. Believe that'd be more than a half degree, though. I'll betcha that's what has been causing my doublefeeds on the last two rounds.

1911Tuner

1st September 2009, 14:28

Believe that'd be more than a half degree, though.

Yeh. It may be a little more. I never checked the exact angle. Just set it 'til it looked right. Like an ol' country cook. Never measures anything. Just adds stuff 'til it tastes right. ;)

niemi24s

1st September 2009, 16:48

Maybe this'll help visualize what happens when the follower's top is laid flush with the feed lips:

http://i129.photobucket.com/albums/p232/niemi24s/P099010001btxt2.jpg

The Ordanace spec follower's rear tab will then diverge from the back of the magazine tube at 1½°.

I guess the specific angle's not all that important, and the main idea is to get the follower so it holds the front of the cartridge up under the feed lips

Regards

barrow

1st September 2009, 22:07

Yeh. It may be a little more. I never checked the exact angle. Just set it 'til it looked right. Like an ol' country cook. Never measures anything. Just adds stuff 'til it tastes right. ;)

Just dont forget that country [/I]hillbillys[I] (like me) who dont know what they're doin need exact recipies! :D

1911Tuner

2nd September 2009, 07:05

Dan...The drawing may represent the spec...but that follower won't work like it should as pictured. The follower angle needs to be opened up...not closed up.

niemi24s

2nd September 2009, 10:28

The follower angle needs to be opened up...not closed up.OK, that follower's rear leg would angle out at its bottom only about half it's thickness behind the mag tube when laid on the outside of the tube, flush with the lips.

To get it to angle out so its bottom would stick out it's whole width (at the bottom) would take about another 1½° of opening.

I've always found describing angle in words to be a real nightmare. Will churn up a pic of what I think you did with Hammerdown's followers when I get back from town.

Cheers

niemi24s

2nd September 2009, 17:26

Hi Tuner:

Does this represent how much you opened up the follower angle on Hammerdown's magazine?
http://i129.photobucket.com/albums/p232/niemi24s/scanLip-Followera.jpg

1911Tuner

2nd September 2009, 17:34

That looks about right, Dan.

niemi24s

2nd September 2009, 20:15

That looks about right, Dan.Great! That eliminates the bother of measuring anything. Just use the magazine tube as the gauge (protractor). So simiple, even my brother-in-law could do it! :D [maybe]

Cheers

barrow

2nd September 2009, 20:19

Guess its the same for Hybrids, GIs and Metalform type lips?

1911Tuner

2nd September 2009, 21:30

ss its the same for Hybrids, GIs and Metalform type lips?

Yep. It's the same for all 7-round magazines with standard followers. Wadcutter type too.

AdventureWolf

3rd September 2009, 02:09

Wait, so to 'open up' the angle your actually closing it up? I must not be following you, sounds like its the complete opposite.

So lets say you modified the follower to the correct angle. That last picture looks as if when you place the follower in the magazine, with the back of the follower against the back inside of the magazine, the follower allows the bullet to sit lower, not higher.

A simpler way to ask is, do you bend the tail end of the follower (looking at it like it is illustrated in those pictures) more toward the back of the magazine, or more toward the front?

Toward the front=closing angle?
Toward the back=opening angle?

Right?

In any case, can someone tell me why this 1.5-3 degree difference in follow angle would make a difference in a 1911s feed reliability?

1911Tuner

3rd September 2009, 05:11

Opening the follower up beyond the angle presented by the magazine, Wolf. Sometimes I'm not clear. Been dealing with an old, sick Collie dog the last few days. Finally threw in the towel yesterday and took him on his last ride...so I'm not really myself, and likely won't be for a while. He was my constant companion, and his absence will be felt for a long time.

In any case, can someone tell me why this 1.5-3 degree difference in follow angle would make a difference in a 1911s feed reliability?

Dunno. It's one of those little tweak tricks that I figured out about 30 years ago.
Somethin' about desparation bein' the mother of invention. I do know that I do it to all my magazines, along with the Wolff springs...and I've got a bunch of'em. 72..and those are are just the range mags...and my range pistols don't misfeed. In the 8 years since I aquired those magazines...and an untold tens of thousands of rounds...I can count on my fingers without using my thumbs the number of malfunctions that I've had that couldn't be attributed to my funky home-cast reloads...and most of those were failure to lock on empty...and those were due to Metalform's odd slidestop shelf design on their followers. A little modification to the slidestop lug corrected that, and it's been smooth sailin' ever since.