1911 feeding question


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ATLDave
February 21, 2013, 12:40 PM
What does it mean if a 1911 occassionally (~2% of the time) fails to go into battery because the rim of the cartridge gets in FRONT of the extractor, rather than slipping behind it? Is that an extractor issue, a magazine spring issue, a magazine lip issue?

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rcmodel
February 21, 2013, 12:48 PM
Almost has to be a magazine issue.

Since the bottom edge of the slide is what is supposed to be what pushes the round out of the magazine?
It has to be against the breech face, and slide up behind the extractor.

How else is it getting out ahead of the extractor if it isn't popping out of the feed lips too soon??

rc

ATLDave
February 21, 2013, 01:16 PM
What if multiple mags of different make generate the same issue?

Would adjustment to COL make a difference?

tipoc
February 21, 2013, 01:26 PM
Would adjustment to COL make a difference?

Over all length? Are you having problems with handloads?

tipoc

ATLDave
February 21, 2013, 01:32 PM
Most of the ammo running through the gun is handloads. I wouldn't say I'm having problems with the handloads, per se, that's just the ammo that is available. Since they are handloads, I can change the cartridge overall length if that's indicated by the intermitent FTF.

Since I measure every round at the end of its completion, I know they're all at the published load lengths, and I know they're all within SAAMI spec. I would ordinarily expect them to be able to feed just fine, but if the characteristics of the particular stoppage indicate an ammo issue, I can look at/tweak that, too.

claiborne
February 21, 2013, 01:54 PM
I had a brand new Dan Wesson PM7 that would not go to full battery (as you desrcibed) at least 2-3 times on each magazine (all flavors of 1911 magazines)
AQfter three trips to the gunsmith and once back to the factory, the pistol still did not function correctly. This was with several types of factory ammo as well as handloads.
I ended up getting rid of the pistol. I hope you can find a solution for your problem. I was into that pistol for about $2500 when I sold it for $800.....boo.

1911Tuner
February 21, 2013, 01:57 PM
I know that this will hit some resistance. I know it. I also know that it's probably futile...but I'll proceed.

Whenever I've run into an intermittent push feed resulting from jumping the magazine, and I've eliminated the magazine...and more than one can be causing it...almost without exception, the breechface is machined at 90 degrees, or ocasionally a few minutes more, instead of the spec dimension of 89'8" which doesn't include a plus/minus tolerance...which means that the dimension is super critical.

When the problem does stem from the magazine, there are at least one of three conditions present...and often two of the three.

The magazine spring is weak, or...in the case of flush fit 8-round magazines...a couple coils short. Most often, it's both.

The top of the follower is smooth, without the tiny dimple...or "pip" as some call it. That silly little bump was put there a century ago by several very smart men, one of which was a firearms design genius of the first order.

The recoil spring is way yonder too strong, likely installed in the mistaken belief that the frame will be destroyed with the standard spring that those people mentioned in the last paragraph determined was correct for the gun...and that was a 14-pound spring...not 16. Here, the problem is still the magazine. The heavy spring just cast a light on it.

With any feed problem, the magazine is always the first suspect. Always. Start there and work your way back.

ATLDave
February 21, 2013, 01:58 PM
The fact that my problem is much less frequent makes me optimistic that it's not going to be incurable. And the gun is new, still in a "break-in" period. (Unlike some, I'm willing to accept "break-in" issues, and, frankly, almost never get a gun without one. At least among self-loaders.)

ATLDave
February 21, 2013, 02:01 PM
Thanks, 'Tuner, I was hoping to hear from you on this! Could you explain a little more about the mechanics/physics of the strong recoil spring causing the cartridge to "jump" the magazine? Is it because its return velocity is so high that it's creating a collision, rather than a push, and the lower-mass cartridge is getting popped ahead of the slide, rather than pushed along by it?

FWIW, the gun came with a stout recoil spring. Maybe the problem will resolve itself as the spring softens up a bit with use. I'm just under 200 rounds into the gun.

1911Tuner
February 21, 2013, 04:14 PM
Could you explain a little more about the mechanics/physics of the strong recoil spring causing the cartridge to "jump" the magazine?

I'll give it a shot.

First, understand that once the slide starts to move and compress the spring, there's a separate action/reaction system in play with the spring as the vectored force between them. The stronger the spring, the harder it pushes on both.

The upcoming round in the magazine doesn't settle down instantly. It bounces around a bit. When the spring starts to push the frame back, the round obeys Newton 1A and tries to stand still. Then the slide impacts the frame, and tries to jerk the gun out from under the cartridge...so the cartridge winds up further forward in the magazine at the very least.

When the heavy spring accelerated the slide at a higher speed, and it collides with the waiting round, its momentum can knock the round completely loose from the magazine, literally chasing it into the chamber with the nose of the extractor against the case rim.

If the extractor snaps over the rim, you're never the wiser...until your extractor starts to lose tension in a couple thousand rounds...or fails. While a proper extractor is designed to allow a snap over in an emergency, it's not supposed to do it indefinitely.

If the magazine follower doesn't have that little bump on top, the round can get loose when the slide impacts the frame...or it can be barely held by the feed lips, and when the slide collides with it...it's out. If you've ever had a slide locked to the rear with the last round lying loose in the port on top of the magazine...there's your sign.

With a weak mag spring and a heavy recoil spring, sometimes the next to last round will jump the magazine...the last round will bump it out of the port...and the slide will feed the last round. If you've ever found live rounds among your brass...heeeeere's your sign.

That little dimple and the correct springs are important.

Fishslayer
February 21, 2013, 04:35 PM
That little dimple and the correct springs are important.

Have you been talking to Ruger? Their SR1911 magazines come with the dimpled follower. ;)

I've become a fanboi for the Checkmate 7 rounders with dimples. I don't think there's a better magazine for $18-ish. Wonder if they make the mags for Ruger.

handyman163
February 21, 2013, 05:47 PM
I've only had this happen once, and on the same range trip, I had a couple of those malfunctions where the round ended up in front of the extractor. I was also shooting my reloads. I changed ONE thing, and it's been cured forever - clean the magazines. Strip them down and clean out the inside. The bullet lube from my lead SWC reloads had gummed up the mag so that the follower was sluggish, and wasn't popping the rounds up properly - unnoticeable when loading/unloading or otherwise looking at the mag, but they were dirty inside. I had people telling me extractor issues, you name it. That's all I did, and kept them clean since and it never has happened again. You may try that, though I'm far from an expert.

And to Fishslayer:
Checkmate does make the Ruger magazines. They have the checkmate follower and hybrid feedlips.
You can get them at TopGun Supply when they're in stock, which of course they are not.

http://www.topgunsupply.com/check-mate-.45acp-8rd-stainless-steel-hybrid-full-size-1911-magazine.html

http://www.topgunsupply.com/check-mate-.45acp-7rd-ss-hybrid-cmf-full-size-1911-magazine.html

tuj
February 21, 2013, 06:02 PM
That little dimple and the correct springs are important.

I don't doubt you, but I have been using Tripp mags with hybrid followers that do not have the dimple and I've never had a mag-related malfunction. Maybe the design of the feed lips on the Tripp Cobramags is a little different?

1911Tuner
February 21, 2013, 06:16 PM
Maybe the design of the feed lips on the Tripp Cobramags is a little different?

Got more to do with that gorilla spring Virgil uses in'em. :D

Ramone
February 21, 2013, 09:30 PM
Got more to do with that gorilla spring Virgil uses in'em. :D
I was just about to ask about that- I had a mag that would sometimes feed the round in front of the extractor (and it did have the dimple, as I recall), and a new spring solved it.

Fishslayer
February 21, 2013, 10:03 PM
Checkmate does make the Ruger magazines. They have the checkmate follower and hybrid feedlips.
You can get them at TopGun Supply when they're in stock, which of course they are not.


That's exactly where I got mine. Should be good for awhile. Got 2 of the blue 7rd and 3 of the SS 8rd. The Ruger comes with one of each. The 7rd spring is noticably more robust than the 8rd.

1911Tuner
February 22, 2013, 06:38 AM
I had a mag that would sometimes feed the round in front of the extractor (and it did have the dimple, as I recall), and a new spring solved it.

The main player is the spring. The dimple...an example of Browning's penchant for redundancy...is a backup in case the spring's tension is less than optimum. It's not a guarantee, but rather a little added insurance. Of course, having the dimple correctly located and within spec dimensionally is also a requirement, and the 1911 is at its best with a magazine that releases the round gradually and late as opposed to many modern magazines that release it too early and too abruptly.

Jolly Rogers
February 22, 2013, 06:48 AM
Got any thing to say about slippery plastic followers some mag builders use??
Mostly on those early abrupt release mags?:evil:
Joe

1911Tuner
February 22, 2013, 06:54 AM
Well, mama always told me that if I ain't got anything good to say...

Seriously, though, enough spring covers a multitude of sins. Tripp demonstrated that in the Cobra...which incidentally...also uses an extended tube and a full-length spring, as does Check Mate's redesigned 8-round unit with their patented "Bullnose" follower, which is little more than a Devel folded follower with a skirt and a dimple. When I was corresponding with them during the development on that one, I had a helluva time convincing them to use a dimple and enough spring. When they finally saw the light, their 8-round magazines became much more reliable.

Krogen
February 23, 2013, 12:45 AM
Thanks to you, 1911Tuner. You oughta' write a book! I'd buy one.

1858
February 24, 2013, 01:20 AM
What does it mean if a 1911 occassionally (~2% of the time) fails to go into battery because the rim of the cartridge gets in FRONT of the extractor, rather than slipping behind it? Is that an extractor issue, a magazine spring issue, a magazine lip issue?

So given 1911Tuner's responses, I'd like to know if you typically experience this issue with the last round or second to last round. You mentioned that the problem occurs with more than one magazine but don't mention when the problem occurs.

Rubber_Duck
February 24, 2013, 07:02 AM
I am just fascinated by all the naunces of the 1911's operation and I've learned even more about what goes on in a 1911 by reading this thread. Thanks for the informative and easy-to-understand answers!

Carry on. :)

Skylerbone
February 25, 2013, 12:39 AM
Might be nice to know what brand 1911 we're talking about as well as there are several known for issues with the breech face, among them the old (and possibly new???) Auto Ordnance and S&W, though they don't hold exclusive patent on machining errors. Any pictures of the brass?

il.bill
February 25, 2013, 12:53 AM
The dimple...an example of Browning's penchant for redundancy...is a backup in case the spring's tension is less than optimum. It's not a guarantee, but rather a little added insurance. Of course, having the dimple correctly located and within spec dimensionally is also a requirement

I purchased several 'Colt' branded magazines from Robertson's expecting to see dimpled followers, but it was not the case. I read one time 'there is no such thing as a dumb queation', but I realize a dumb guy like me can still ask a question, so here goes: Can a properly located to specs dimple be added to the follower carefully using a center punch struck from the bottom?

1911Tuner
February 25, 2013, 06:37 AM
I purchased several 'Colt' branded magazines from Robertson's expecting to see dimpled followers, but it was not the case.

You probably ordered 8-round Colt magazines, which are nothing more than Shooting Stars with Colt's pony on the baseplates. A picture will tell more of the story.

Can a properly located to specs dimple be added to the follower carefully using a center punch struck from the bottom?

No. It's a punch and die operation.

Here's a picture comparing the three basic feed lip designs.

On the left is the original "Hardball" type with full tapered feed lips and late, gradual release.

On the right is the "Wadcutter" type, with parallel lips and early/abrupt timed release.

In the middle is the "Hybrid" which combines the feed/release characteristics of the other two.

http://i40.photobucket.com/albums/e243/1911Tuner/tn_lips_comparison_top.jpg

il.bill
February 25, 2013, 09:57 AM
1911Tuner

Thank you for the photo. That picture is easily worth a thousand words. I would like to save that on my computer for reference, if you do not mind.

I purchased five 7-round NOS 'Colt' magazines from Robertson's Trading Post for $75 delivered a while back. They say 'Colt 45' on the base plate, but there is no Prancing Pony nor follower dimple anywhere to be seen. Two or three do not lock the slide back when empty, but they feed reliably so far.

Thank you again for sharing your knowledge so often for the benefit of so many of us. Keep up the good work!

1911Tuner
February 25, 2013, 10:04 AM
They say 'Colt 45' on the base plate, but there is no Prancing Pony nor follower dimple anywhere to be seen.

Those are counterfeits. The manufacturers get around the infringement question by not using the horse logo, and lead uninformed buyers to believe that...because it says COLT.45 or COLT 45 Auto...that it's a Colt magazine.

I used to see these a lot at gun shows selling for as little as 5 bucks a copy. Many of them were actually pretty decent magazines after changing the springs. I had one that lasted for years before the baseplate welds finally failed. Others that were outwardly identical weren't worth bringing home.

Incidentally, Colt hasn't made magazines in house in over 50 years. They contract for them made to their specs...usually Metalform, Check Mate, and OKAY Industries...but recently, they've bought them from others.

ATLDave
February 25, 2013, 10:25 AM
So given 1911Tuner's responses, I'd like to know if you typically experience this issue with the last round or second to last round. You mentioned that the problem occurs with more than one magazine but don't mention when the problem occurs.

I haven't noticed a pattern to it yet, but I'll start paying attention and report back if it manifests again.

ATLDave
February 25, 2013, 10:27 AM
Might be nice to know what brand 1911 we're talking about

Kimber. No brass pictures at the moment, but is there something you're looking for?

Skylerbone
February 25, 2013, 11:25 AM
An flat indentation on the base of spent brass caused by machining errors in the area above the ejector. My S&W after initial clean up (later scraped smooth by a smith).

http://www.thehighroad.org/attachment.php?attachmentid=171395&d=1347242582

The AOs were cut with an angle rather than a radius at the J Cut (port side when in hand) but neither of these errors would be common with a Kimber. That makes magazines/springs the primary suspect, with a more remote chance of breech angle running a very remote second. Still something to look for.

Powderpacker
February 26, 2013, 04:09 PM
I have had this problem at times. My magazine springs have never been replaced. 1911Tuner, whose springs do you recommend?

I have a series 80 Gold Cup. I shoot 200 grain LSWC's over 5 grains of W231. I think the Gold Cup uses a 16# spring. Would I be better off with a 14# spring?

Jimmy

1911Tuner
February 26, 2013, 07:12 PM
My magazine springs have never been replaced. 1911Tuner, whose springs do you recommend?

Wolff, but be sure to order the right spring. If you're not having any problems related to the spring, there's really no need to replace them, other than as a preventive measure.

Recoil spring: As long as the slide makes full travel rearward and goes to battery reliably, either one will do.

gym
May 13, 2013, 10:37 PM
It's nice to see true "genius" explain things we take for granted. It's amazing how something that looks so simple, could be that complicated. Great job explaining the nuances of the extraction issue.

1911Tuner
May 14, 2013, 07:05 AM
I have a recurring, sometimes maddening habit of asking "What is it for?" It's made me unpopular in certain circles and in certain situations, because there is just as often no practical answer to the question.

We can often determine the answer to that question by studying and thinking...by asking of the designer as if he were standing there: "Why did you do that?" What is its purpose?" "What is it FOR?"

In the case of that little dimple, I asked that question several years ago, and...being unable to sort it out or get Johnny Browning to answer me...I decided to embark on an experiment with a pistol that had long since proven its dead-nuts reliability.

I removed it from the followers of a half-dozen magazines and started shooting. Almost immediately, I started observing two intermittent problems had hadn't been present with the dimples in place.

The first, and most frequent, was the slide locking open with the last round loose on top of the magazine lips. The other, less frequent, but still repeated often enough to draw a conclusion...was the round chambered ahead of the extractor, stopping the slide out of battery...but there was a variation that wasn't readily apparent and one that I noticed quite by happenstance.

Whilst preparing the fired brass for reloading, I noticed a sharp burr kicked up on the edge of a few case rims, along with a telltale mark further inboard that matched the shape of the extractor nose. A mark and a burr that I'd never noticed before...leading me to coin one of my favorite and oft-repeated axioms...

"Just because it's functioning is not proof that it's functioning properly."

Curious, I pressed on.

I started single-loading the pistol by locking the slide to the rear...chambering a round by hand...and dropping the slide, forcing the extractor claw to snap over the rim. Of course, the burr and mark were reproduced on every case.

Before long, I noticed a loss of extractor tension. Forging ahead after resetting it...it happened again. Shortly after the 4th retensioning cycle...the extractor hook snapped off flush with the breechface.

You may draw your own conclusions.

Krogen
May 14, 2013, 10:31 AM
1911Tuner: I'd sure like to see you write a book! I'll place my order right now, pre-publication!

As to "what is it for?" we have a practice at work called Five Whys. You can see where it might lead. Simply keep asking why for every answer to the previous why. Of course, it doesn't have to stop at five, but must not be fewer than five whys. This can get comical, intense, annoying etc. but it makes people think; and some folks angry. I believe I'll add "what's it for" to my repertoire!

tipoc
May 14, 2013, 12:59 PM
A good thread and good posts.

tipoc

RainDodger
May 18, 2013, 03:51 PM
Yes - this is all excellent info for 1911 magazines!

I have a number of 8 round Sig mags. ONE of them (the others appear fine) tends to lock my slide back prematurely and the round in the mag is partially pushed forward but not free of the mag's feed lips yet. It's still captive, but the slide locked back.

Is that sounding like a weak magazine spring? The dimples are present in the follower and the other Sig mags work okay. I'm running these in a Springfield TRP with an 18 lb. Wilson recoil spring. Thoughts about it?

Thanks a lot.

1858
May 18, 2013, 04:36 PM
... original "Hardball" type with full tapered feed lips and late, gradual release. ... "Wadcutter" type, with parallel lips and early/abrupt timed release ... "Hybrid" which combines the feed/release characteristics of the other two.

I removed it [little dimple] from the followers of a half-dozen magazines and started shooting. Almost immediately, I started observing two intermittent problems had hadn't been present with the dimples in place.

You may draw your own conclusions.

The obvious question here is did you test each of the magazine feed lip styles described above? Did you observe the same failure with all three feed lip types?

1911Tuner
May 18, 2013, 07:03 PM
The obvious question here is did you test each of the magazine feed lip styles described above? Did you observe the same failure with all three feed lip types?

At the time, all I had was WW2 era USGI magazines, so no.

I've noticed the same failures in several modern "wadcutter" type magazines with smooth followers.

And I'm havin' a little trouble wrappin' my head around why different styles has anything to do with it. The problems were never noted with the stock followers, and immediately appeared when the dimple was removed with a file, and then went away again when the followers were replaced.

That pretty much only leaves room for one conclusion.

wally
May 18, 2013, 07:54 PM
I've no doubt the dimple on the follower is important for the last round. But I'm having a very hard time seeing how it can have any effect if the push feed is happening with three or more rounds left in the magazine.

I was having some ignition problems with Tula primers in a 9mm 1911 and went to a 26 lb hammer spring. Made the pistol push feed city! Went back to the stock spring and things seem back to normal. Same as too strong a recoil spring the recoil foce doesn't decouple from the frame and basically leaves the round sitting there with the magazine and gun moving out from under it. With a loose enough grip I could watch it eject the top round and feed the one underneath.

1911Tuner
May 18, 2013, 09:33 PM
I've no doubt the dimple on the follower is important for the last round. But I'm having a very hard time seeing how it can have any effect if the push feed is happening with three or more rounds left in the magazine.

That part of the discussion just sorta evolved from the original question...and you pretty much figured it out with the inertial effect causing the round to jump the magazine. Although it's usually a weak mag spring at the root of that, too much recoil spring can make it more likely to happen.

Steve in Allentown, PA
May 19, 2013, 04:05 PM
I was having some ignition problems with Tula primers in a 9mm 1911 and went to a 26 lb hammer spring. Made the pistol push feed city!
I wonder if a lighter recoil spring in combination with the 26lb hammer spring would have worked.

The heavier the hammer spring, the more resistance the slide will encounter on its rearward travel. This should have the effect of slowing down the slide. I can't figure out how this would negatively affect the feeding of the next round.

wally
May 19, 2013, 04:31 PM
I wonder if a lighter recoil spring in combination with the 26lb hammer spring would have worked.

I switched in the lightest recoil spring I had when I switched in the hammer spring, how low you can go on the recoil spring is pretty much set by the force it takes to strip the rounds off the magazine.

The 9mm 1911 is much more prone to push feeds than the .45 because the rounds are significantly shorter and all the manufactures seem to put the spacers to compensate at the rear of the magazine which reduces the amount of feed lip available to hold the rounds. I use Checkmate and Metalform mags with Wolf extra power mag springs. I wasn't expecting push feed problems with the stronger hammer spring, but I wasn't totally surprised by it either.

Steve in Allentown, PA
May 20, 2013, 09:10 AM
. . . how low you can go on the recoil spring is pretty much set by the force it takes to strip the rounds off the magazine.
Quite right. I just can't figure out the physics behind the phenomenon of a heavier hammer spring exacerbating an inertia feed condition.

The slide is having to overcome the increased resistance of the heavier hammer spring. This should have the effect of robbing momentum from the slide movement. Less momentum, less tendency for the round to end up forward of its starting position in the magazine, right?

Where's Einstein when you need him?

1911Tuner
May 20, 2013, 09:33 AM
I just can't figure out the physics behind the phenomenon of a heavier hammer spring exacerbating an inertia feed condition.

If you ever watch a very slow-motion video of a locked breech pistol firing, you'll notice that there's very little movement of the gun until the slide impacts the frame...and then it torques upward and backward violently. By robbing the slide of speed and momentum, it doesn't impact the frame with as much gusto.

Installing a heavy recoil spring has that effect, but you reach a point of diminishing returns pretty quickly, and the frame begins to be shoved backward rather sharply by the power of the recoil spring alone. Remember that, once the slide starts to move, a separate action/reaction system comes into play, with the spring providing the force vector between slide and frame.

By using enough mainspring...or maybe going a pound or two heavier...the slide's acceleration is resisted the instant the gun fires...before it gains much speed and momentum.

This effect is compounded with the use of a small radius on the bottom of the firing pin stop...as per Browning's original design...by reducing the mechanical advantage of the slide in accelerating the hammer's mass and compressing the mainspring.

The original firing pin stop radius was .078 inch...or 5/64ths. I've gone as small as .050 inch without ill effects...and it does tame muzzle flip to a noticeable degree.

Steve in Allentown, PA
May 20, 2013, 11:06 AM
. . .that there's very little movement of the gun until the slide impacts the frame

. . . the frame begins to be shoved backward rather sharply by the power of the recoil spring alone.

By using enough mainspring...or maybe going a pound or two heavier...the slide's acceleration is resisted the instant the gun fires...before it gains much speed and momentum.

This effect is compounded with the use of a small radius on the bottom of the firing pin stop

Tuner, I follow your posts with great interest and have bookmarked many of them on multiple forums across the web. I understand everything you've written here and have incorporated these concepts in my tinkering.

But, I don't understand how, in this particular case, a heavier hammer spring (main spring) increases the possibility of an intertia feed.

gym
May 20, 2013, 12:08 PM
On a simpler note, which readily available magazines are best for the majority of 1911's. Preferably something that is easy to get hands on, like a Wilson or McCormick?
And is there a disadvantage to using the 8 rouders in guns that come with 7 rounders, "I can't possibly see one, but why not ask"

wally
May 20, 2013, 01:14 PM
And is there a disadvantage to using the 8 rouders in guns that come with 7 rounders, "I can't possibly see one, but why not ask"

My experience is that a properly setup 1911 will run fine with simple GI style magazines and wadcutter vs. tapered feed lips makes no real difference. Needing "fancy, expensive, special" mags is putting on a band-aid to cover up the real underlying problem IMHO.

The downside of the 8-round mags is they are prone to push feed the last round since they lack the dimple on the follower, which can be hard on the extractor eventually and they will sometimes give a feed failure on the last round. I carry the 8-round (7-round for Officers sized) in my pistol figuring if I don't get the 9th shot I was no worse off than if I'd had used a 7(or 6)-round mag.

I've always used the CMC "shooting star" or Mec-Gar for the eight rounders (although I prefer the CMC for carry because of the flush fit) and "GI forgery", CMC, Metalform or Checkmate for the 7-rounders -- doesn't much matter when the gun is setup right, as long as the mag spring is good and the follower has the dimple in the right place.

On alloy frame guns the point on the "devel", aka shooting star" 8-round follower can booger up the frame around the bottom of the feed ramp. When the last round chambers the follower gets dragged forward and the point hits the frame, its worse if the slide fails to lock back on the last shot. Its basically only cosmetic damage, but can be prevented by rounding off the point of the follower which is what I've always done to the CMC 8-rounders.

The original firing pin stop radius was .078 inch...or 5/64ths. I've gone as small as .050 inch without ill effects...and it does tame muzzle flip to a noticeable degree.

Small radius firing pin stop is pretty essential with a 10mm 1911 firing full power loads.

1911Tuner
May 20, 2013, 01:21 PM
But, I don't understand how, in this particular case, a heavier hammer spring (main spring) increases the possibility of an intertia feed.

It doesn't. It decreases the chances. I must've misread your question.

wally
May 20, 2013, 02:26 PM
Quote:
But, I don't understand how, in this particular case, a heavier hammer spring (main spring) increases the possibility of an intertia feed.
It doesn't. It decreases the chances. I must've misread your question.

I've not mis read my actual experience with a 9mm 1911. 26lb hammer spring made it push feed city. Replacing the stock hammer spring and no push feeds in 400 rounds since the return to normal -- I don't run enough recoil spring to snap the extractor over the rim, so every push feed is a stoppage.

Steve in Allentown, PA
May 21, 2013, 03:01 PM
I've not mis read my actual experience with a 9mm 1911. 26lb hammer spring made it push feed city. Replacing the stock hammer spring and no push feeds in 400 rounds since the return to normal -- I don't run enough recoil spring to snap the extractor over the rim, so every push feed is a stoppage.
Well, I guess we can chalk this up to black magic and gremlins.

I wonder if the better way to tune 1911 funtioning is to start with the lightest recoil spring that will strip and chamber rounds reliably then find the hammer spring weight that will allow the slide to travel fully to the rear.

So, instead of starting with a 23lb hammer spring and swapping recoil springs until you find the one that works best, you proceed from the opposite end. Just wondering out loud.

wally
May 22, 2013, 09:29 PM
Well, I guess we can chalk this up to black magic and gremlins.

I don't believe in such.

The 9mm 1911 is much more prone to push feeds because the rounds are so much shorter in OAL than .45ACP. The fact that just about everyone puts the spacers in the magazine at the rear of the follower in an attempt to compensate for the shorter OAL makes less feed lip available to hold the top round under recoil.

Basically the top round can move forward enough under recoil, before the slide has decoupled from the barrel that less than half the feed lips are left trying to hold the round, then it doesn't take all that much of a frame impact to have it about jump out and result in a push feed when the slide moves forward.

Its all a matter of timing and balanced forces. I'd wager that if the "spacers" were in front of the follower (like Tanfogilo has done with their large frame 9mm & .40S&W mags) that the issue would greatly reduced and the 9mm 1911 would have a better reputation.

I love mine but they can be finicky and take a bit of playing around to get running right.


So, instead of starting with a 23lb hammer spring and swapping recoil springs until you find the one that works best, you proceed from the opposite end. Just wondering out loud. That is basically what I did, I went to the lightest recoil spring I had and one step above stock for the hammer spring. It just didn't work for me, in an attempt to stop the push feeds with some very short OAL, 20+ yo reloads the ammo shortage has had me dig out to shoot up. I wasn't expecting it to be worse with normal OAL rounds, but it clearly was.

Steve in Allentown, PA
May 23, 2013, 08:20 PM
The 9mm 1911 is much more prone to push feeds because the rounds are so much shorter in OAL than .45ACP. The fact that just about everyone puts the spacers in the magazine at the rear of the follower in an attempt to compensate for the shorter OAL makes less feed lip available to hold the top round under recoil.

I fully understand.

That is basically what I did, I went to the lightest recoil spring I had and one step above stock for the hammer spring. It just didn't work for me . . .

This is the thing that has me confused. Everything worked until you substituted in a heavier hammer spring. Then things didn't work as well. If the amount of force imparted to the frame by the slide impacting the recoil spring guide rod is the root cause of the inertia feed then reducing that force would seem to be the key to solving the problem.

I thought that a heavier hammer spring would reduce that force and thus reduce the tendency for inertia feeds.

But just the opposite happened.

I guess I'm just too dull to grasp what's happening or I missed something important in an earlier post.

wally
May 23, 2013, 08:42 PM
If the amount of force imparted to the frame by the slide impacting the recoil spring guide rod is the root cause of the inertia feed

Its part of it, the other part is how much the frame/magazine jerks back before the slide/barrel decouple. The net resultant of these two effects is what ends up happening. The first effect is minor for .45ACP as they don't have much space in which to move forward until the slide/barrel decouple and they don't give up ~1/8" of feed lip to a "spacer" from the git go.
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