Help diagnose these failures.

Out of about 100 rounds, I had two types of failures, three in total.

1: TWICE, following firing, the slide did not move fully forward. I looked into the pistol, and saw the new round partially into the chamber. I whacked the rear of the slide with the palm of my hand, only to bruise my hand. It was locked up solid. I whacked the bottom of the magazine, and racked the slide back, only to find that the extractor had not yet engaged the partially loaded round. I had to pull the mag, and clear the jam. The locked up round showed no signs of deformation.

2: ONCE, following firing, the new round was "stood up" behind the chamber. The nose of the round was up against the top of the chamber, and the slide was as closed as it could be. I pulled the slide back, and gave a "uumph" toss right, the round flew wide, and I continued to fire.

The failures were on two mags, and I do not believe the same mag each time. The failures were near the end of about a 100 round firing session. At the beginning of the 100 rounds, the pistol was pristine clean. The failures were noever the first of last rounds in the mag. They were in a string of fire.

Any thoughts on common causes of these types of failures?

#1 sounds like an ammo problem. #2 could be several things.

Firearm used?

How "new" is the gun, ie how many rounds already fired though it?

Ammo brand/type used?

How experienced a shooter are you?

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Originally Posted by bruce333

#1 sounds like an ammo problem. #2 could be several things.

Firearm used?

How "new" is the gun, ie how many rounds already fired though it?

Ammo brand/type used?

How experienced a shooter are you?

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Pretty good bit of info not here to accurately diagnose your problem(s) It would help a lot to know what type of firearm we are talking about and the ammo used. And weather or not the gun is new, used, how used if used?:watching:

The pistol is an AMT 45 Backup.

Ammo was WWB JHPs 230gr.

Both mags are factory AMT. No second market.

I was told the pistol had been fired "a couple hundred rounds". There was no indication of issues or not from the seller. This was a 3rd party sale.

Looking at the pistol, it does not show any abuse or signs of extreme usage. I, however, have scratched it since I got it. I'm not saying it could pass for new in the hands of an experienced smith, but it likely could have fooled me, had I not known AMT has not built pistols for a bit. I'm not even sure High Standard is really producing them.

I ordered a Wollf replacement spring for the recoil spring, as I know small pistols wear out those pretty quick. I polished up the slide and frame rails until the action was smooth. I also polished the feed ramp and where the barrel lug rides the assembly pin. Hopefully this will help some. At those points, smoother is better, for sure.

As for me, I'm an experiences shooter, but not a pro by any means. I have no recollection of any time in my life where guns were not part of it. For my 4th Birthday, my Dad bought himself a Marlin 22 39D. It became mine officially, once I could lift it long enough to fire a decent shot. (Still have it...) For pistols, I've fired thousands upon thousands of rounds since I was a kid. I've owned pistols of my own since I was 17 (20 years ago). Some were good and some bad. I tried IPSC for a season back in the mid 90s. Wasn't enough time to really do it...

The AMT has a bad rap, for sure. I like the pistol enough that if I can work with it, or even send it off, and get a good reliable pistol, I'll do that. I just like it... No good reason, but I do. I had a 380 many years ago that worked well. I hope to get this one up to snuff.

If it is unrecoverable, I'll dump it off on someone else who thinks they might can fix it up, and try another small 45... Maybe a Kahr CW...

I think I'd try a different brand of ammo before I started blaming the gun. I've case gaged WWB and always found a few rounds that fail to go in the gage all the way.

You should try FMJ. The feed ramp could probably use some polishing too.

Yeah - I'd try some different ammo. I could be that the recoil spring was too tight not letting the action open all the way can causing feed issues. This could be because of the bulk ammo as well. The polishing you did will probably help. It couldn't hurt anyway. The problems with bulk ammo is that they will have pretty loose specs as to what is good or not.

I've seen some people wanting to make a gun appear better to stretch the recoil spring to make it look like it's tighter. The problem lies in that doing that can make the action not work properly.

Please let us know how it works out once you replace the spring and/or try some different ammo. That WBW is pretty good ammo most the time but all guns are different and will not just eat anything sometimes.

Thanks for the input!

I'll snag a box of ball ammo (of some type) as well as a couple of different JHP loads to experiment with.

I did do a once over on the feed ramp already, as well as the slide area and barrel lug.

All in all, it may just need a little TLC.

If all it cycles well is ball, I could live with that...

Thanks again.

Many small .45s are quite grip-pressure-sensitive; grab that thing like you're choking a rabid weasel to keep it away from your face, and see if an extra-firm grip helps prevent any more stoppages.

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Originally Posted by DJ Niner

Many small .45s are quite grip-pressure-sensitive; grab that thing like you're choking a rabid weasel to keep it away from your face, and see if an extra-firm grip helps prevent any more stoppages.

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If his recoil spring is a little tight that may well be the main issue. Any "limpness" in the wrist will not allow the spring to work properly. Especially if it's a bit tight.

Quote:

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Originally Posted by DJ Niner

Many small .45s are quite grip-pressure-sensitive; grab that thing like you're choking a rabid weasel to keep it away from your face, and see if an extra-firm grip helps prevent any more stoppages.

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+1...My thoughts exactly. I have no problems with FTF or FTE with my PT1911 unless I get lax with my grip pressure.

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Originally Posted by FHBrumb

The AMT has a bad rap, for sure. I like the pistol enough that if I can work with it, or even send it off, and get a good reliable pistol, I'll do that. I just like it... No good reason, but I do. I had a 380 many years ago that worked well. I hope to get this one up to snuff.

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I feel your pain.

I have a CZ RAMI sitting at the factory, awaiting its turn, with similar problems. I replaced all the springs, polished everything gently, and struggled through about 600 rounds, trying to make it eject and feed reliably...because it just shoots so damn good.

Good luck.

Have you tried cleaning the magazines? A small bit of crud can cause the follower to drag delaying upward movment of the cartridge stack.

I did give the mags a spray with Gunscrubber. They do not come apart, so that's all I can do...

As for the grip thing, yes. I'm sure a soft grip will make for a poor performing 3 inch 45ACP. But I'm also pretty sure I can hold a pistol for 100 rounds. And I'm not sure how the two failures I mention would ne initiated by a limp wrist. I'm not saying impossible, but I just don't see it. Keep in mind the first failure was a hard lock up. The second was a round that stood up.

Looking at the second one, it was like the feed lips held the bullet too long. But for it to only have happened once kinda makes me think that's wrong. Possibly the round was a little short OAL. Then it would have not reached high enough on the hood as the mag released it, and instead of bouncing down into the chamber, it just stood right up...

But the first failure has me stumped...

The magazines do come apart. It's fiddly, but pretty easy once you've seen it done.
Depress the follower as far down into the magazine as you can, and insert a thin pin punch through the first set of witness holes to trap the magazine spring, but not the follower. The follower can now be shaken free of the spring and, if you turn the magazine upside-down, it will either fall out, or just fall against the feed lips so you can rotate it out with your fingers. Put your palm over the magazine's feed lips and pull the pin punch out, and you'll find the spring in the palm of your hand. Pull it out.
Clean the follower, spring, and the inside of the magazine, and do not lubricate it. Lubricant traps dirt. Magazines don't need lubricant.
Put the spring back, being careful to turn it right-side-up and right-side-front, push it down and pin-punch it in place, slip the follower in and drop it onto the spring in its correct orientation, and pull the punch out.

You might have a good gunsmith polish the pistol's feed-ramp and also inside its barrel-hood, to slick-up the feeding cycle.

My AMT .45 Backup functions well with Federal Hydroshok JHPs. If all else fails, go to FMJ ball ammunition. Do not use "Plus-P" cartridges in a .45 Backup.
Use heavy, slow bullets for best control. High-velocity loadings make hanging onto this tiny pistol extremely difficult.

To use a miniature .45 like the Backup, you have to have lots of practice and experience with a full-size .45 first. This is not a gun for beginners.
If you do not have lots of experience (be honest with yourself, now), put the Backup aside for a while, and learn to shoot a full-size pistol very well before you pick it up again.

My primary pistol is an XD-45, and I shoot it quite well. I can hit an 8 inch Shoot-N-See pretty much all day at 25 yards. No kidding... My "other" pistol is a 5 inch 686, which I can print OK on the 8 inch Shoot-N-See out to 50 yards with factory sights. I do not often shoot much past 15 yards, but I can, and can consistently.

I can hit an 8 inch Shoot-N-See with this AMT pretty well out to about 30 feet. I have not moved back any further. I guess I don't feel the need to. I feel like I'm shooting pretty low to hit center, but side to side, it's right on the money.

I'll try taking the mags apart as you mention. Certainly getting them clean won't hurt a bit.

How are you re-compressing the spring, before the follower goes back in? That sounds like the tricky part. Thanks for the info!

And again, if it ends up being a "ball only" pistol, I could live with that, as long as it feeds 100% of the time.

Quote:

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Originally Posted by FHBrumb

...How are you re-compressing the spring, before the follower goes back in? That sounds like the tricky part...

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I use a section of dowel that just happens to be the right diameter and length, both to take it apart and to put it back together. You could also use your pinky-finger, or anything else that fits. A relatively right-angled end helps, but isn't really necessary.
It sounds a lot trickier than it is, really.

I commented about the shooting experience you need, to use a mini-pistol, because the method of disassembling an AMT Backup magazine is the same as that for a 1911's, with which many people are quite familiar. Thus, I wasn't sure about your experience-base.
I apologize, if I offended you.

If you're hitting low at 10 yards, the gun's difficult trigger may be the cause. There's an easy sort-of trigger-job you can do with abrasives detailed in an article in the July/August, 2008, issue of American Handgunner, on page 71.
It'll help, and it may be all the help you'll get, because most gunsmiths won't work on this little gun.
If you're adventurous, you could detail-strip it and polish everything in the trigger and hammer assembly that rubs against anything else, which is what I did.
Whatever you do, do not cut the hammer spring. It is included in the recoil-spring calculation, and changing it may adversely affect your pistol's operation.

Quote:

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Originally Posted by FHBrumb

I did give the mags a spray with Gunscrubber. They do not come apart, so that's all I can do...

As for the grip thing, yes. I'm sure a soft grip will make for a poor performing 3 inch 45ACP. But I'm also pretty sure I can hold a pistol for 100 rounds. And I'm not sure how the two failures I mention would ne initiated by a limp wrist. I'm not saying impossible, but I just don't see it. Keep in mind the first failure was a hard lock up. The second was a round that stood up.

Looking at the second one, it was like the feed lips held the bullet too long. But for it to only have happened once kinda makes me think that's wrong. Possibly the round was a little short OAL. Then it would have not reached high enough on the hood as the mag released it, and instead of bouncing down into the chamber, it just stood right up...

But the first failure has me stumped...

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I suggested checking grip pressure as it is a known problem-causer with small .45s. I won't tell you I understand WHY it causes problems (except in a general sense), or exactly WHAT type of problems a loose grip can cause. But I can tell you that it's easy to check, doesn't cost anything but the price of the ammo you will expend (which you'll be shooting anyway, next time out), and many folks who didn't think it could possibly be the problem have been very surprised when it turned out to be the case. It's not a case of "holding" the pistol, as much as you are giving it a firm base for the recoil mechanism to push against. Large/heavy-frame guns have enough inertia to provide their own solid base for functioning; small/light guns often need help in the form of a firmer-than-normal grip.

If you don't want to burn through 100 more rounds with a tight grip to see what happens, try the opposite; hold the weapon loosely (but still safely), with an unlocked wrist, and fire a magazine or two of ammo. If grip pressure is a factor in your stoppages, you'll probably get a higher percentage of them during these test mags.

Good luck with the problem; hope you can figure it out. There are few things more annoying than a weapon that won't function reliably.

I wasn't offended by your experience comment. But I do at times grow weary of the "aquired taste" kind of comment sometimes you can geet on a board. To me, if something is an aquired taste, I'm generally not not interested. I do know that a short 45 is about as troubled a design as can be. If it works at all, it's pretty much on the fringe of failure.

BTW, on the mag thing, my last 1911 was nearly 15 years ago. Strangely, in those days, I just didn't like them.:oops: I went to revolvers after that, and only in the last year or so, looked back at autos, going forst to the XD. I'd almost swear that my 1911 mags had a removable floor plate. ALMOST swear... Alcohol was going through braincells almost as fast as my pistols went through ammo back then. Not my best days. I'm not even sure what brand I was using. Right now, I'm salivating over a 1911 again, and don't really know why. Older and wiser? Dunno...

The trigger sucks. I'm looking all over to find a spring company I can send a new hammer spring to and ask for replacements. Whatever strength this one is, I'd look for one at 105% length and 90% strength. Then 105% and 80% to experiment. With this spring, no amount of polish will help my particular pistol. It's smooth enough. All I feel is spring...

I'll shoot the pistol again, once we are above zero for a day. I can try hard gripping and soft to see what happend. As indicated, I'm going to be shooting it anyway...

Thanks to all for the input!

FHBrumb;
If you do get a new, softer hammer spring, please let me know (by PM) how well (or poorly) it works for you.
I have been told, by a very competent gunsmith, that the hammer spring has a lot to do with how the pistol handles the recoil impulse, since the hammer's geometry is very deeply involved in retarding the slide's rearward movement.
Because of that advice, I have resisted the impulse to change the hammer spring of my pistol, not wanting to adversely batter its slide or barrel.
I found that a detailed polishing of the whole trigger/trigger-bar/hammer assembly, and where all of it rubs, makes a huge difference. Smoothing and polishing the trigger's face helps a lot, too. You can also (very carefully) polish both surfaces of the trigger-bar/hammer interface with very good results.

Looking at the pistol, I'd have to agree that the hammer helps lock the mechanism. It's like a spring loaded cam, locking it a smidge. But I think that a 10%ish reduction would not change much in that regard. I'm no gunsmith, however... The recoil spring I got from Wollff was a plus power recoil spring as well. That should help some.

I'm looking for a stock AMT spring online to carry around to some spring places locally, and just see what I can find. If nothing else, I'll get online, and see what's out there.

I think I want to stay close to the gauge of wire (certainly not thicker), a little longer, but not as stiff, keeping the same number of coils. Somewhere, I'm sure that spring exists. It might not be part of a pistol, however.

If I find it, and experiments a bit, I'll keep you in mind.

I found a website about the "fluff and buff", and did all recommended. I also polished the underside of the frame where the hammer face runs along it. My thoughts were to keep as much slide velocity as possible during cycling.

Next time I'm cleaning, I'll polish the rest of the triggering components. Again, it certainly couldn't hurt.

FHBrumb;
For the hammer spring, maybe see either Brownell's or Numrich Arms (Gunparts Corp.).
Yeah, I wouldn't modify the hammer spring unless I had a reliable replacement at hand, ready to use. (I don't own a spare.)

New Subject (sort-of):
Beware, if you wear a wedding ring. Mine rips up the skin of my strong-side hand's ring finger, when I use a two-hand hold on the little monster.

I have no problem holding my shots at center-of-mass, at up to about 20 yards. The groove is quite enough a sight, to do that.
Past about 20 yards, I'm no good any more anyway, even with a full-size pistol. Arthritis takes its toll...

Good luck! Let me know how things work out.

Yup, I just ordered one from Brownell's. $11.04 shipped.

I'll be hauling it all over for a while. I can hear it now... "You only want ONE?" :oops:

Once it gets here, i'll measure it out, and key the information into a few spring selling websites, and see what pops up.

Your second thought-
Shooting right now requires gloves anyway. I'm up in Wisconsin. Once we thaw out, I'll try to keep in mind what you said about the ring. It should not take much blood loss for it to come back to me...:smt023

Thanks again for the input.

Well... With 50 rounds of Blazer Brass and 50 rounds of WWB JHPs, I went back to shoot the AMT again. The lock up failure did not make an appearence. Improvement. but, the pop up failure did. Looking carefully, I noticed this time that it was always on the last round fired from the mag. It happened with FMJ and JHP. It might just need a better mag spring.

I had 4 failures in the 100 rounds, and now I pretty much cannot move my trigger finger. That trigger is just too much for any kind of high round count shooting.

I've decided that it's just not going to make me happy, and I'm selling it.

It's replacement might be a Kahr 45 or it might be a S&W 65. I'm not sure which.

If anyone is interested in buying it, PM, and I'll link you to the GB auction. I'm selling it as a good loss, as I just do not feel the pistol is worth what I paid for it just a few weeks ago.

Thanks again and again for to the folks offering help.