1911 feed problem

[log man]

Jam 1 is from an inertia fed problem where the round has come out ahead of the extractor. This can be due to too light a recoil spring, or weak mag spring or oil on the mag.

The Sig extractor is possibly the cause of the other malfunctions, in my opinion. I have re-shaped mine to mimic the internal extractor geometry, where the extractor rides on the rim vs. in the case groove as the original Sig does, and probably the cause of the malfunctions.

LOG

 

[1911 guy]

CCS3, I've "met" logman on a couple forums. He sometimes has some very interesting and informative things to say. He just can't help being juvenile and confrontational, even when saying the same thing as everyone else.

So don't expect an answer to your question. And don't expect an apology if it was aimed at you.

 

[CCS3]

It doesn't bother me if he doesn't answer. I won't loose sleep over a comment by a rude but helpful person.

The helpful trumps the rude.

 

[log man]

Well, gosh that went well. I thought I did respond, and clarified the best, I could. Post 25, was in respectful response to post 24.

LOG

 

[CCS3]

So who should get a grip? That's what I wanted to know.

 

[log man]

??Anyone not realizing that an inertia fed round was in front of the extractor to begin with, and not rejected by an overly tight extractor. If I misunderstood the inference, then it is simply my mistake at adding an explanation. Just got up, 6:30 am here.

Such as this.



LOG

 

[CCS3]

Great. That explains only one of the listed problems with photos that are being discussed here. Tight extractors, insufficient extractor hook to breech clearance and a poor extractor profile coupled with tight chambers and a very rough slide finish are the cause of the rest of the issues Sig pistols are having, at least from what I have examined on the bench.

I have also come across feed ramps that were "polished" side to side with what looks like a very coarse Dremel bit, chambers that were "throated" with what looked like a scraper and have had to finish ream almost all of the ones that have come into the shop. Now these were brand new pistols straight off the assembly line.

My post deals mostly with jam 3

 

[CCS3]

Logman, would you suspect slow slide speed as being the cause of the case getting in front of the extractor?

 

[log man]

Yes, Jam 3. From post 25.

The Sig extractor is possibly the cause of the other malfunctions, in my opinion. I have re-shaped mine to mimic the internal extractor geometry, where the extractor rides on the rim vs. in the case groove as the original Sig does, and probably the cause of the malfunctions.

I found the same. Extractor tips too sharp and shaving brass in the bottom of the groove.

Barrel makers do not finish ream and neither do factory assemblers, Wil Schuemann laughed when I asked him about this issue. Even their AET barrel chambers are cut with a boring bar. His response well taken was , "Always finish ream."

LOG

 

[CCS3]

Maybe the slides surface on the disco track and the transition from the track to the breech face should be looked at.

 

[log man]

Logman, would you suspect slow slide speed as being the cause of the case getting in front of the extractor?

No, I would not see that as the cause of an inertia fed round. If the slide stops before fully chambering, and the slide can be closed by a gentle push, perhaps too light a recoil spring, or too tight an extractor.

A cartridge in front of the extractor can be mimicked when hand cycling at slow speeds as bumping the cartridge head with the slide pick-up rail will often bump it ahead of the extractor. This does sound like a weak recoil spring, however I feel the slow hand cycle is not the same thing, and have not been able to release a slide with an 8# recoils spring to mimic an inertia fed round.

So, it sounds contradictorily, as a weak recoil spring can cause inertia feeding, as it allows the slide to hit harder as in the picture, so it isn't happening on closing, but at the end of the recoil stroke.

I prefer lighter recoil springs too begin with, flatter cycling, and do not have inertia feed problems. If however I purposely oil up a mag I can duplicate it.

This brings up another extractor tuning point I find beneficial. That is to tune the extractor to smoothly jump the rim when the slide is released from the half way point, where the slide leaves hammer contact. So, even with an inertia fed round you would never know.

With the Sig extractor sharp as it is from the factory, tuning will be required
for this.

LOG

 

[BBBBill]

There's a wealth of info available that describes proper hook geometry, shape and dimensions. Recommend that all concerned with extractor read and study as much as possible, as a misbehaving extractor is a common area for problems. As noted, the hook should not bottom out in the extractor groove (in 45ACP), should not climb the extractor bevel on the case, and should have the proper relief on the bottom to allow the round to slide under as it feeds. Hook to breachface dimension is often grossly excessive (and would require a custom extractor to correct on any external type). And of course the noted recoil spring and magazine issues. Lots to look at with a critical eye....

 

[log man]

CCS3, I've "met" logman on a couple forums. He sometimes has some very interesting and informative things to say. He just can't help being juvenile and confrontational, even when saying the same thing as everyone else.

So don't expect an answer to your question. And don't expect an apology if it was aimed at you.

Interesting observation, yet "juvenile and confrontational", for what purpose I'm unsure. While my sense of humor, and failure to comprehend what one is thinking, may bring on doubt, rest assured understanding is my perpetual goal. Both for those I address and myself.

LOG

 

[1911Tuner]

Inertial feed?

What is this "inertial feed" that you speak of?

The round chambering ahead of the extractor occurs because it moves forward in the magazine when the slide impacts the frame...then, while the magazine is still barely clinging to it...gets hit by the slide on its way back to battery...knocking it into the chamber with the slide chasing it.

Jumping the magazine happens when the slide impacts the frame, and if it happens on the last round, the slide locks open with the cartridge lying loose in the port. If it happens with more cartridges in the magazine under it...the jumper is kicked clear of the port by the next round up...and that round gets chambered. If you've ever found a live round amongst your empty brass...heeeeeeeeeere's yer sign.

In both instances, the problem is with the magazine and usually the spring. "Usually" because on the last round...if the magazine follower doesn't have that silly little bump on it to keep the cartridge from leaving the magazine when the slide impacts the frame AND the mag spring isn't up to snuff. That's what the bump is for...to make sure that the last round stays under control and feeds the way it's supposed to...even when the magazine spring has gone soft.

So many magazine manufacturers these days don't seem to understand why that little bump was put there to begin with, and shooters have been complaining about having to retension and replace extractors ever since.

This brings up another extractor tuning point I find beneficial. That is to tune the extractor to smoothly jump the rim when the slide is released from the half way point, where the slide leaves hammer contact. So, even with an inertia fed round you would never know.

Many years ago, a man named John Browning designed the nose of his extractor to allow the claw to snap over the rim in the event of a lost or damaged magazine...not to mask a malfunctioning magazine....figuring that a single-shot pistol is better than a pistol that can't be fired in such an event.

 

[log man]

Inertial feed?

What is this "inertial feed" that you speak of?

The round chambering ahead of the extractor occurs because it moves forward in the magazine when the slide impacts the frame...then, while the magazine is still barely clinging to it...gets hit by the slide on its way back to battery...knocking it into the chamber with the slide chasing it.

Jumping the magazine happens when the slide impacts the frame, and if it happens on the last round, the slide locks open with the cartridge lying loose in the port. If it happens with more cartridges in the magazine under it...the jumper is kicked clear of the port by the next round up...and that round gets chambered. If you've ever found a live round amongst your empty brass...heeeeeeeeeere's yer sign.

I believe we are in agreement for the most part, except the inertia question. The round is standing still, and the gun jerks, recoils, out from under the cartridge held by the inertial force, of a body at rest tends to stay at rest.

In this case the slide does not ever contact the cartridge until it catches up to the round in the chamber. Take another look, the slide is still in full recoil, and the cartridge has entered the chamber on its own, or perhaps better to say the cartridge stood still while the gun lurched out from under it and the chamber swallowed it up.




I quite realize the 1911 was designed to jump the rim, however many will not due to the extractor's nose shape or the inability for it to flex far enough in its channel. Either is tunable and should be.

Nice to see you back, honored your first post is in response to me. Glad you're well.

LOG

 

[1911Tuner]

In this case the slide does not ever contact the cartridge until it catches up to the round in the chamber. Take another look, the slide is still in full recoil, and the cartridge has entered the chamber on its own, or perhaps better to say the cartridge stood still while the gun lurched out from under it and the chamber swallowed it up.

In that picture, the rim of the case is still in the magazine. When the slide runs forward, it'll knock it the rest of the way in. If the extractor climbs the rim, the shooter will never know it happened.

If it happens often enough, the extractor tension will start to degrade. If it keeps happening, the extractor claw can fail.

If it had completely escaped the magazine, it would be on the ground, or headed that way...either tossed out when the pistol torqued upward, or bumped out by the next round. Or...if it was the last round...lying loose in the port with the slide locked.

Those are fairly common, and the magazine is always the cause.

It can't ride forward that much as the slide moves rearward. It can't. The center rail doesn't uncover the magazine and let the cartridge rise until the slide is within about a half-inch of full travel...and even less if it's a Commander.

While the slide is moving toward the rear...before it uncovers the magazine...the center rail is dragging the round backward. So, there's a very narrow window of opportunity for the round to jump the magazine.

If it jumps at the instant of impact, it's out of the port from muzzle flip. If it jumps just after impact, the rising round will bump it out of the port. At the most, it will get caught horizontally between the breechface and the barrel hood, with the slide trying to feed the one that came to feeding position.

A true "double feed" in which a live round is in the chamber with another live round against it is exceedingly rare. I've never actually seen it happen, and I've never known anyone personally who's had it happen. IMO...it's one of those "perfect storm" things in which everything has to happen in just the right way...or the wrong way.

 

[log man]

Been to UCIrvine Med and back, sorry.

Never seen one jump out, but know they can, and do, have seen several double live feds at matches however, and had one myself before I got a handle on it.

If you put a little STP on the feed lips you can get a lot happening all through the mag, you can bet on that.

Yes, the window is narrow, but it does happen, and this picture was taken because the member that owns the pistol was having the problem, and took the picture to show it.

Another interesting thing about the rail dragging the round backwards, especially on the last round, it does, and as the rail corner slides over the case head groove it flips the cartridge, like tiddly winks. Nose up, then back down again as the rail corner dozes it into the frame ramp. Or if the recoil shock is great enough, it starts its journey out of the mag, the rail isn't what finishes the job as if it were, the extractor would have a shot, but it's too late,too far gone, and just dozes the cartridge into the chamber, if the extractor doesn't jump the rim then it's over.

1911's with a buffer especially Kimbers, as the slide notch is slightly forward, so it can't clear the slide stop, will lock open as the last cartridge titters from the rail crossing the groove, allowing the follower to kick the slide stop up, and will lock open with the one in the mag. Take the buffer out and it will function normally. This especially with CMC's Devel follower, which if out of adjustment, is rocky. Chip and I discussed this at length and discovered that if the leafs where off just a little, you could pretty much bet the slide would lock open with one in the mag. Dial in the leafs and return the buffer as a test, and no failures.

Little things rock the boat.

LOG

 

[1911Tuner]

If you put a little STP on the feed lips you can get a lot happening all through the mag, you can bet on that

Why would anybody do that, except to cause something to happen that doesn't normally happen?

Another interesting thing about the rail dragging the round backwards, especially on the last round, it does, and as the rail corner slides over the case head groove it flips the cartridge, like tiddly winks.

If you say so.

 

[log man]

If you put a little STP on the feed lips you can get a lot happening all through the mag, you can bet on that

Why would anybody do that, except to cause something to happen that doesn't normally happen?

Gun oil from an overly lubed 1911 splashing on the lips and some folks believe that part of mag maintenance is to clean and wipe with an oily rag, sounds good, but will instantly cause feeding problems. The STP comment was for the extreme, and being a NASCAR advertiser thought you'd appreciate that. Nothing really different from STP or oil, was always claimed to just be very high viscosity oil. Andy did a good job!

So word to the wise, do clean your mags, but leave clean and dry.

I've modified hundreds of mags and it is amazing how much oil the manufacture leaves, or puts in their mags, fine for shipping and while in storage, but if they aren't clean when used they will contribute to miss feeds.

LOG