Double Feed on last but one

[JulChris]

Hi, I am new to this forum an I have a question for Tuner and other experts.
I have two 1911, a Springfield and a Kimber, both 5”.
With the former I have shoot 7K rounds, without a malfunction (of course, after 3K I have installed and tuned a Wilson BP extractor).
The Kimber, a Custom II with external extractor, had problem from day one: stovepipe, FTEj, stem bind.
I thought the major culprit was the extractor, so I have iron out all problem building a new extractor and radiusing all corners in the slide.
I get rid of the extractor chamber loaded indicator function and now it snap easily over the rim of a chambered round, and eject cases straight and at over 6 feet: 1500 rounds and no one problem.
But then, at circa 1600, I have encountered two Double Feed, always on the last but one round, in 7R MecGar magazines, with 230 and 200 grs.
So I switched to a Wolff 18,5# spring and for another 500 rounds all was ok.
Then I tried to cause another Double Feed polishing and oiling the cases, holding the Kimber in every mode: limp and “hard” wrist, upside down, up and downhill. No more Double Feed: I thought to have resolved all problems.
But yesterday…. another Double Feed (some conditions)!
What do you think? No last round problem, even with slippery ammo and with magazines with very short lips and no dimple (as same Tanfoglio made), but 3 DF at the 6th round in trusty MecGar.
Can someone explain if this problem can be fixed or is this not eliminable for sure in the 1911 pattern? (Three jams in over 1000 rounds are not a big deal, but here we are accustomed to the reliability of the Beretta and Glock…)
Chris

 

[Old Fuff]

Why did you switch to an 18.5-pound recoil spring? Yes, that could be part of your problem.

I have little experience with external extractors in 1911 style pistols because I have made a practice of avoiding them like a plague. Maybe Tuner can help you better with this then I can. In any event I would observe that the cartridge rim is supposed to feed under the extractor hook, and not snap over it. While your extractor may (or may not) be all right, you could have a problem with the little coil spring that tensions it. Browning by the way had used external extractors in earlier pistols, including the Colt model 1905, which was his first commercial .45 pistol. However he abandoned the external extractor concept in later prototypes that evolved into the model 1911. Perhaps he had a reason?

Tuner has gone to great lengths to explain about magazines, and the importance of using springs with the correct tension, and flat followers with the little dimple. Those that choose to ignore his wise advice sometimes suffer the consequences.

I notice that you are new to this forum, so perhaps my previous statements were a bit harsh, but it becomes a matter of answering the same questions over and over and over ...

Well anyway, I'll wait and see what Tuner's comments are, and then perhaps go further into the issues. In the meantime I suggest that you use the forum's search feature and look into the considerable number of threads Tuner has started or responded to on double-feeding.

 

[JulChris]

Thank Old Fuff. I am new to this forum as a member, but I have read (almost) all the threads regarding the 1911 platform.
I would explain that:
The new extractor function flawless, as the cartridge rim feeds smoothly under the hook as has to be, but just in case the cartridge slipped ahead, my new extractor snaps easily, avoiding a failure to go battery (as sometime happens in standard 1911 with the internal one).
I am very fond of my Custom II: ragged holes at 20 Yds are the norm, but I can’t understand why (in rare occasions, but it happens) the last but one cartridge become loose and jam the pistol.
As told, I have tried to induce a double feed shooting a lot of ammo, but with no “fortune”.
How is possible that only the last but one cartridge slips ahead, while the very last no?
Chris

 

[Old Fuff]

JulChris:

On reflection the Old Fuff will apologize to our new member for the abrupt and somewhat unfriendly answer to his first thread and post. In his defense however he will plead that another cup of morning coffee was needed, and he was suffering from a case of frustrations.

The 1911 platform has a well deserved reputation for reliability when it is manufactured in the way the designer intended. Unfortunately what various companies are offering today are bastardized versions that sometimes sharply deviate from the original guns in ways that invite malfunctions. Pistols, such as Beretta's and Glock's are made by single manufacturers, who either make the parts and other components they use, or obtain them from contractors over which they maintain some degree of quality assurance. With the exception of Colt, that has become a relatively minor player in the overall market, 1911 pistols are assembled, not manufactured, by firms that purchase all of the components from outside sources. In addition, original material specifications are ignored because they are seen as being too expensive, and design changes, such as external extractors have been incorporated primarily if not completely for the purpose of achieving cost savings.

Magazines, which are a critical component within the system, seldom have correct springs and/or followers.

Consequently it should not be surprising that a number of these guns malfunction, but rather that so many of them do work - which occasionally they do. But this is of no comfort to those who end up with a problem child.

Double-feeding is usually associated with an out-of-spec magazine, or sometimes extractor tension. An extra-heavy recoil spring may also contribute because it can shorten the slide's rearward cycle and increases its forward velocity. The condition only happens when a number of factors occur at more or less the same time, and for that reason predictability and repeatability are difficult unless something is seriously rather then marginally wrong.

The next time you have one of these jams look at it carefully and see if the top (second to last) cartridge is in front of the extractor, or the base is against the breechface with the rim under, or coming under the extractor hook.

I continue to suspect a weak magazine spring perhaps combined with a too strong recoil spring.

Edited to add:

Tuner says ... Colt...Springfield...Kimber...McCormick SS...Most of those are Metalforms anyway...and I have a suspicion that Powermags and Baers are too.

Standard 7-round follower with the dimple and 11-pound Wolff springs. Set the extractor tension correctly. If you use that combo and still have feeding problems, see a pistolsmith who understands the 1911.

 

[JulChris]

Yes, I can blame the magazine, and, probably, I can get rid of this last problem reverting to magazines with dimple and longer lips… but I’m just curious how this type of jam can happen.
But ... even with new magazines, how can I be confident that the pistol is absolutely reliable, if I not understand the jam mechanics?
In the last trip to the range over 300 rounds were ok, one Double Feeded, and the following 250 were ok again. Must I shoot thousands rounds?
Ok, Ok, my firearms are used for recreational uses only, so it is not a big problem a casual jam, but I am always in quest of perfection...
In Short:
three Double Feed on the 6th round with the same magazine, but with different ammo: a factory (MFS 230 FMC) and two handloads (200 and 230 Jacketed on full charge of W231), in over 2000 rounds, with 16 and 18 ½ springs.
Too few Jams to be scientifically analyzed, but too much to trust the pistol!
Chris

 

[BluesBear]

Why not just replace the spring and follower in the magazine?

I have several Mec-Gar magazines. Although all of mine are the eight round variants both with flush floorplates and with the slightly extended finger rest.

The finger rest models use the same follower as the Mec-Gar severn rounders and I've never had any sort of malfunction with them.
The Mec-Gar flush fitting eight round magazines use an almost exact copy of the original Devel follower. The Shooting Star follower, while licensed from the original Devel patent, is noticably different.

 

[wally]

I'm having a hard time understanding what this "double feed" is. Anyone got a photo of what the failure looks like?

I've never seen a jam involving two live rounds being out of the magazine.

--wally.

 

[Old Fuff]

JulChris:

Do you use the magazine(s) in question In your Springfield (with what I presume is a conventional extracor)? If so, it would seem that you don't get the double feeding problem you see in the Kimber.

You may have a situation where, on rare occasion, the extractor on the Kimber starts pushing on the rim of cartridge #6 and pushes it forward while the breechface picks up the rim on cartridge #7 while cartridge #6 continues to move forward. If I understand correctly, you find that cartridge # 6 is either floating, or is partially chambered with the rim in front of, rather then under the extractor. If so we have a strong clue.

 

[wally]

the extractor on the Kimber starts pushing on the rim of cartridge #6 and pushes it forward while the breechface picks up the rim on cartridge #7 while cartridge #6 continues to move forward

I've never experienced anything like this, thought I'd seen every feed-extraction-ejection failure mode, guess not.

What I still don't understand is even if round 6 is being pushed by the extractor instead of having slipped under it, there still should be no room for round 7 to move up when the mag feed lips releases round 6 since the bottom of the slide (which is what has stripped found 6 from the mag) should be blocking it. Or is round six an empty when this happens?

Again, I'd love a photo to see what I'm missing here.

--wally.

 

[Old Fuff]

If anything like this happens you will usually find the top cartridge is laying loose in the ejection port and sometimes it may be reversed with the bullet pointing backwards because as it was pushed free of the magazine lips it flipped over. The cartridge below it will end up jammed against the feed ramp, or it may be a classic stovepipe and you'll find a loaded cartridge (#6) on the ground. It is also possible to find round #7 is chambered, but a loaded round (#6) on the ground.

That's why I'm interested in finding out if the round that was left on top of the magazine had the rim coming up under the extractor, or was in front of it.

 

[BluesBear]

Wally, what I think Old Fuff is trying to describe is the strange phenomenon where the sixth round remains stationary due to inertia and is stripped from the magazine as the gun moves rearward in recoil. Sometimes this round will flip 180º.*

The sixth round is then laying loose on top of the magazine as the breechface tries to strip the seventh round normally from the magazine.

What you end up with is a round (#6) that, by whatever applied force, is trying to enter the chamber in a straight line as another round (#7) is attempting to occupy the same space by being fed from below as was intended.


In my limited experiance this is often a weak magazine spring or faulty magazine feed lips problem.




*Sometimes round #6 will only flip 90º and will wind up nose in the air, slammed shut in the ejection port. (Referred to as "Morning Wood".)

 

[Old Fuff]

Good description, and yes that is what I am trying to say.

Since what happens to JulChris is on so few occasions, it is difficult to analyze exactly what is happening. Hence a lot of speculation goes on in place of solid advice. But a "Tuner Specification" magazine would be a good place to start, and a weaker recoil spring might be part a solution too. His Kimber is obviously oversprung, which speeds up the slide's return stroke - maybe faster then the magazine spring can occasionally position the second-to-last cartridge.

That brings up another question: Is JulChris using any kind of plastic buffer on his recoil spring guide?

John Browning, through years of trials, tests and experimenting came up with a great platform. But when it is modified outside of the original specifications it doesn't always work like it should. Ya' can't blame the gun for this.

 

[TheDutchman]

I have a Kimber Pro Combat series 1, that would not function 100% with Wilsons, MetalForms, Chip McCormick's, and Kimber factory mag. However with the Mec Gar mags is cycle and feed correclty with no problems. Also if anyone notice that Kimber has started to ship Mec Gar mags with new guns.

 

[JulChris]

Old Fluff,
To respond to your question (our time zones are too apart to respond quickly..)
I don’t use any buffer.
I have a batch of magazines for the Springer and another for the Kimber.
I have not tried to swap them, but the MecGars on the former always functioned flawlessly.
I’ll try on the net trip to the range.
In the 3 Double feed the slide was correctly behind the rim of the last cartridge.
Attached is a photo of a Double Feed simulation, as happened on the field.
You note that the slide in stripping the last round, while the previous one has left the lips and is barely chambered, and this must have happened during the rerward travel of the slide.
I cannot figure how the extractor can play any role in this jam, as the 5th case has been ejected regularly and vigorously.
I cannot blame the 18.5 spring, either. The first 2 jam were with a 16# and I thought that a heavier spring would reduced the impulse of the slide hitting the frame, with a lesser chance that the round on top of the magazine could move forward due to inertia.
A faster return could lend to slide over rim, but not at the jam in the photo.
Certainly the culprit is the magazine, but why only the 6th and not the last round?
Why so rarely?
NOTE: in the pic you see the two LIVE ROUNDs.
(the extractor is not the original, but the one manufactured by myself, and is flawlessy... I hope)
Chris

 

[Old Fuff]

JulChris:

Ya' took a good picture. To answer one question: Why always the 6th and 7th rounds? Remember, when you fully load a magazine the spring is as compressed as it can get, and the top round in the magazine is being pushed against the lips with maximum pressure. But as each round feeds the follower and remaining cartridges go up, and as they do so the spring pushes less and less harder. When you get to the last two rounds (#6 and #7) they are being pushed upward with the least force. You can easily understand this as you know that the first cartridges are easier to load, then the last ones, and it the last ones that are loaded into the magazine that are first to be fired.

That's why a strong magazine spring is important, and the basis of Tuner's recommendation for an 11-pound Wolff spring. The stock springs are often too weak in the first place, and over time may take a set and be even weaker.

Inside the magazine it is the round(s) under the top round (or the follower on the last one) that pushes the cartridge up to position it in front of the breechface, and start it under the extractor. The cartridge's rim must come up and under the extractor, and unlike some other pistols (the German Luger for example) the extractor hook does not snap over the rim.

In the Browning design, extractor tension on the edge of the rim is very important. JMB designed an internal extractor that was in effect a long, flat spring that could be slightly bent to get the right tension, and hold it thereafter. Today, some manufacturers (Kimber being only one of several) have discarded Browning's extractor because they find it to be too expensive, and it requires an assembler who knows how to set it. Again, skilled help costs extra money. The external extractor they use is tensioned by a small coil spring, and other then changing out the spring there is no way to adjust the tension. Further, if the hole that holds the spring (and sometimes a plunger) gets filled with fouling and dirt the coil spring can't properly compress.

In your picture I see three things.

1. Apparently cartridge #5 was fired, extracted and ejected without a problem.

2. Cartridge #6 is lying in the breech, and the rim is not under the extractor as it should be. In fact it is well in front of the extractor.

3. The slide's face is still behind round #7, indicating that round #6 was propelled forward by its own momentum, not the breechface (that is still behind round #7).

I think at a minimum, your magazine needs that 11-pound spring.

The shape of your homemade extractor may be fine, but have you checked the tension?

 

[wally]

Many thanks, now I understand what is going on. I've never experienced this. My gut reaction if I did would be to deep six the mag in question if I couldn't try it in another gun.

My only comment is it may only happen when the mag is nearly empty because the weak mag spring is compressed less and therefor exerts less total upward force, also the gun is lighter at this point with a lower rotational moment of inertia helping it rotate away form the round during recoil.

As to why not the 7th & 8th instead of only the 6th & 7th? You said its rare, so perhaps you've just not seen it yet, or it could be the ratio of upward spring force minus downward bullet weight is only in the critical region with three rounds left in the magazine. Have you tried lighter bullets (assuming its 230 gr you've been shooting, otherwise I'd try heavier)?

--wally.

"Morningwood" I've seen as a variation of "ride over feed' problems in double stack 1911s -- stronger mag springs and cleaning/polishing interior mag surfaces has always been the cure.

 

[JulChris]

Old Fuff,
I have adjusted the tension of the extractor inserting a brass plunger at the rear end of the spring.
I agree with You on the "dirt" issue: all Jams were with the pistol full of debris.
Next Saturday I'll test at least 500 rounds, and so will do my shooting partner.
He is experimentig the classic "last round" jam in his Kimber I, due to magazines without the dimple. We have made a die and punched all his follwers.
Teh next Saturday ll'be an hot one.....
I'll keep You informed.
Chris

 

[Old Fuff]

The location of that dimple is critical. Rather then try to "dimple" your other followers, see if you can borrow (or otherwise get one) out of an older commercial Colt or USGI magazine, and try it in your own box. While the dimple is important, the stronger spring is much more so. For fast delivery of all kinds of acessories, tools and parts, go to:

www.brownells.com

Be sure to order a copy of their print/hardcopy catalog too. You will find all kinds of interesting stuff.

 

[JulChris]

I’m a long time customer of Brownell’s.
As per the USGI followers.
I have bought some surplus magazines from a big importer, but they all have failed short after, and I cannot trust their followers too.
But I have found a very well used original WWII magazine; I think it was lost during the war and left loaded from that time!
Its body is rusted and discolored, the spring is pitted and eroded from rust, the rear side shows five crescent protrusions from the rims of the cartridges. Well. I use it regularly and it have NEVER had a failure!

 

[wally]

I have found a very well used original WWII magazine; I think it was lost during the war and left loaded from that time!
Its body is rusted and discolored, the spring is pitted and eroded from rust, the rear side shows five crescent protrusions from the rims of the cartridges. Well. I use it regularly and it have NEVER had a failure!

Survival of the fittest!

Hope everyone has had a safe and happy 4th of July and said a little prayer for the boys over in Iraq.

--wally.

 

[Old Fuff]

JulChris:

I didn't mean to suggest that you should go to aftermarket trash copies of USGI magazines. Most of them are junk. However you can put one of the followers (that aren't too bad) in a quality body with a decent spring to experiment with for 500 rounds or so. If this combination should work you know what direction to go for serious purpose magazines.

Or at least order an 11-pound Wolff spring out of Brownells before Saturday, and set up your best magazine with it.

>> But I have found a very well used original WWII magazine; I think it was lost during the war and left loaded from that time! Its body is rusted and discolored, the spring is pitted and eroded from rust, the rear side shows five crescent protrusions from the rims of the cartridges. Well. I use it regularly and it have NEVER had a failure! <<

Maybe it's trying to tell you something ...