What Kind Of Jam Is This?

[Jammer Six]

I've never seen this type of jam before.

It happened with a Springfield 1911 with a Wilson 47.

Suggestions?

38734

[Ronbo256]

insufficient extractor tension. Is that the last round?

[feets]

That's a live round. I would suspect a magazine issue.

[Jammer Six]

Yes, it's the last round in the magazine.

There is no round in the chamber-- the spent round extracted properly, but then this round jumped base up.

I've seen last rounds fail to chamber, but I've never seen a base stuck up in the air like that.

[KYCaster]

Weak magazine spring.

Jerry

[EMC45]

Mag spring or feed lips.

[44man]

Round jumped the feed lips! Try another magazine.

[white eagle]

What Kind Of Jam Is This?
log jam !

[gray wolf]

Last round jam into the front of the barrel, sometimes they will hit the barrel straight on and put two distinct V shaped dents in the front of the case.
Last round is unsupported --no rounds under it to hold it up.
Weak extractor lets the round drop and the angle of the round changes.
A good place to look is extractor tension, or replace extractor.
Mag spring would have to be very week to cause this.
Do a search on how to check the extractor tension, very easy to do.

[cajun shooter]

The very first thing to change when you have a feeding or function problem is the Magazine.
It has been my experience that the next thing with the 1911 design is the extractor.

[MtGun44]

Feed lips spread, possibly soft metal or more commonly cracked rear corners
of the mag at the top letting them spread and release the round. Another
possiblity is weak spring and/or dirty mag letting it hang up for a sec and then
popping up in midcycle.

I have seen two that chambered the round backwards, quite a sight.

Bill

[Jammer Six]

After the execution of Project Magazine, in which I replaced all of my magazine springs and filed until all magazines would drop free out of all guns, I went back to the range.

This picture was taken on the seventh round of the test.

The magazine is a Wilson 47, seven round magazine, with a new spring.

[flinchnjerk]

Wilson's slick plastic follower? Full-house load? My guess is that inertia caused the last round to jump the mag, but the slide's return stroke caught the round before it escaped the gun completely, or was chambered by "push feed"( in which case you'd never have noticed a problem). Try loading the mag with two rounds only... a number of times. For the last round use fairly fresh brass... with rims that have no "dings" on the circumference (mark the rounds so that you'll know which of the retrieved brass was the last round). After firing, check the brass for "dings" on the rim circumference. If you find 'em, the last round's jumping the mag, and you're getting "push feeds" ( the ding's caused by the extractor snapping over the rim).

[thegreatdane]

my guess is mag lips.

[Jammer Six]

With the mag theory, (and recognizing the PM I got, thank you) that would mean this jam would be restricted to the one mag, yeah?

So I can test it.

If other mags (I have a bunch of Wilsons and a bunch of Metalforms) produce the same jam, either the other mags have the same problem or it's something else.

Have I got that right?

[thegreatdane]

That sounds like a reasonable approach. You might try measuring the feed lip gap on the questionable mag vs all others. Make sure and label the bad one. It would be a real pain to get it mixed up with the other good ones.

[ColColt]

Measure them from the back end. Most should run around .375" . If they get up to a spread of .399-may as well toss them.

[Jammer Six]

"from the back end"?

At the back end? From the back end forward?

I'm sorry, I don't understand that.

[Dan Cash]

Colt means from the rear of the magazine where the base of the cartridge would be when loaded in the magazine.

Another thought: If this is occuring with one magazine only, take a magnifying glass and look at the rear of the magazine just below the lips and check for a crack at the corner. Rare with high quality mags but always a possibility. A crack in the magazine will cause this failure.

[Jammer Six]

I'll check the mag for cracks.

Okay. To measure, then. From the rear of the mag to where?

[runfiverun]

across the lips

[Jammer Six]

Okay, thanks. Across the lips, at the back of the mag.

[Jammer Six]

Uh, oh.

At first glance, it looks like a couple of them are over .400.

[edsmith]

A weak recoil spring can cause that.

[Jammer Six]

Okay, a few answers.

I measured 39 magazines. First off, that means that somewhere, one of my magazines made good an escape.

Of the mags I measured, none of them even came close to .375. None of them were even .380. The closest I got to that was .384.

I had fourteen mags over the cutoff of .399, ten of which were .404.

Two of the ones over .399 were Wilsons, the others Metalforms.

So how tight is this .399 cutoff? I have mags a few thousandths both ways.

Here's a couple pictures, showing how I measured them. Let me know if that's the measurement you guys have been talking about.

In other news, I'm putting together a spring weight scale, and as soon as I get my fish scale, I'll measure recoil springs.

[thegreatdane]

I wouldn't toss the wide ones. Why not bend em a little bit. Worth a try anyway.

[Jammer Six]

Yup, gonna.

I'm looking for anvils on Brownell's as we speak. Seems to me, Back In The Day, on another continent, we'd get drunk and beat magazine lips onto anvils. So I'm hoping that Brownell's has the anvil I need for modern lips.

[ColColt]

Jammer-I don't know where the cutoff point would be but if I had any that was .390 or greater I would take them out of service...personally. I have several new CM mags, one came with my Commander and another I bought direct from CM and they both mike at .375". You can reform the lips but they'll spread sooner or later.

[Jammer Six]

Oh, man...

That would leave me with about 6 mags...

Have any of you guys come up with a reasonable way to beat on lips?

Brownell's wants ninety five dollars for their anvil & yoke set!

[MtGun44]

SMALL brass hammer, ~3/8" SMOOTH steel rod held in a vice horizontally. Put the rod under
the lip (kinda like a round) and tap many times to move the lips. Any cracks in the
rear corners? This is common, adn REALLY spreads the lips.

Bill

[Jammer Six]

Huh. This is a practice thing, isn't it?

You measure to tell when you're done, I take it?

Are Metalforms set to a different spec than Wilsons?

[flinchnjerk]

Uh...er... not to belabor the obvious, but if it were a spread feedlip problem - or any other of the suggested problems... why did it wait for the seventh round to manifest itself? If it were a feedlip width issue, you'd have noticed it when you stuffed in the first round (and every round after)... it'd be sitting noticeably higher than normal. The seventh round loaded - that is, the top round - would've escaped the mag when you removed your fingers from it, since it's at that point when the mag spring is exerting the most upward pressure - it's at its most compressed state. If all's happiness in 1911 heaven for the first six round, but there're misfeeds on the seventh (or last if other than a seven round mag) round - it's a mag spring and/or follower problem.
The Wilson mags that I have and have seen have a rounded or circular feedrail cutout... not square with sharp corners where stress risers lurk. I'll give Wilson mags this - I've never seen a cracked one.

[leftiye]

Across the rear opening of the feed lips.

[W.R.Buchanan]

I ran into this problem head long on my Mauser to .45 ACP conversion yesterday.

I bought a Novak mag and it would not push the round up under the extractor.

The problem is the mag follower. And it happens on the last round.

I too consulted Brownells and the first thing I noticed is that my Mag has a step on the front of the follower. This step does not support the round in it's normal position when the feed lips release it. The round wants to nose over and the extractor misses it when it does.

On my mauser conversion the round hangs up in the process and will not chamber . The second to the last round last still has the full length of the cartridge to support and guide it up under the extractor. The last round is totally controlled by the mag follower and you can see in the pic how mine has a step and so when the feed lips release the cartridge it noses over in front of the extractor which results in a jam. I might add it does this every single time on the last round.

I bought this mag used at the gun show and it was in nearly perfect condition and now I know why it was there in the first place. I bought a Pachmayer follower from Brownells for $4.00 and am pretty sure it will fix the problem. This is not an unknown problem and there are several brands of mags that have it.

Here is several pics showing what I am talking about. Note the first pic is the follower with its step. Second shows the round just barely held by the feed lips and 3rd is just after it is released. You can see how the last 1/4" of the cartridge is being pushed up by the follower but there is nothing preventing the nose from falling down. Pic 4 shows a round ready to be released but with the next round supporting it.

Why this mag has a follower like this I have no idea, and nearly all of the replacements and the originals have some kind of follower that goes all the way to the front of the mag.

http://castboolits.gunloads.com/imagehosting/thum_182084f13558c92332.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=3466)http://castboolits.gunloads.com/imagehosting/thum_182084f1355b2e6150.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=3467)http://castboolits.gunloads.com/imagehosting/thum_182084f1355d0a3efe.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=3468)http://castboolits.gunloads.com/imagehosting/thum_182084f1355e0b8700.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=3469)

Hope this sheds some light on your problem.

Randy

[leftiye]

Weld or solder a piece of sheet metal to the top of the follower (with a notch cut out of it to clear the slide stop finger so that the slide does not stay open with the last round partially chambered)?

[35remington]

WR, have you tried any tapered lip GI or hybrid magazines? These let the round rise closer to the extractor before they are released.

Larry Gibson mentioned that in his own Mauser conversions these types of magazines fed more reliably than the straight lipped type.

[W.R.Buchanan]

I am no expert on 1911 mags as I have never had a 1911.

What do tapered lip GI mags look like, and what is a hybrid mag? Pics please.

Randy

[MtGun44]

Here.

http://castboolits.gunloads.com/picture.php?albumid=161&pictureid=2355

NOT originally my picture, copied it from the web somewhere, possibly here. Too good
not to have a copy.

Bill

[sailinon]

It's threads like these that make me glad I'm here. Thanks for all the pics and info folks.