Live round ejected with previous spent casing - ideas?

[PakWaan]

My new Sig P938 is ejected live rounds. The gun is new, bought it last month, it has a total of 700 rounds through it. Today I ran 100 rounds through the gun, using 2 different magazines, each loaded with 6 rounds every time. On 5 occasions, after shooting 5 rounds, the slide locked to the rear and the gun was empty. I found a live round on the ground each time.

During one of the cycles, a live round is being ejected with the spent casing. But since it goes bang again with each trigger pull, I'm guessing it must be the last round in the magazine that gets ejected, because I can't imagine it happens in the middle of a magazine and still loads the next round in addition to the one that got ejected.

It stumped the gunsmith at my LGS today, where I was shooting it.

I was thinking magazine lips or springs, but it happens with 2 magazines and they are both new. I borrowed a new 3rd magazine from the gun store, and twice, on the last round of the magazine, this is what I got:



I just got it back from Sig yesterday, because it wouldn't feed hollow points. They polished the feed ramp and now it feeds HPs with no problem. Sounds like it needs to go back to the factory again.....

 

[WestKentucky]

Most likely a bad mag. Try to recreate the flaw, then start ruling out the variables. I would guess bent feed lips on the mag.

 

[Miked7762]

You're hitting the slide stop while firing. It's easy to do on such a tiny pistol.

 

[Trent]

The only time I've ever had this happen to me was on a Glock 19, fire one round and it'd spew a live one out the ejection port, or jam.

In that case, it was a magazine with a crack running up the top middle rear causing the issues.

The magazine lips should prevent this from happening. Maybe the two you have are both from a bad batch?

Engaging the slide stop while firing would be hard on the notch on the slide, but shouldn't cause extra rounds to fly out of the magazine, MikeD.

 

[BSA1]

It sure sounds like classic bad feed lips on the magazines but on two brand ones???

I had a mini 1911 Detonics which for me was a hard shooting gun due to it's recoil. I had to really work on using a tight grip and locked in arms for it to eject and feed correctly. I eventually sold it and downgraded to small 9mm's and have not had that problem since.

The most obvious suggestion is to have someone else that is experienced with 1911's shoot it.

 

[fastbolt]

First off, I have no experience with that SIG pistol and its magazines.

As a longtime firearms owner, instructor & armorer I've experienced & observed last-round ejection of live rounds to usually be the result of weakened/defective mag springs, mag lips being too wide/out-of-spec or an issue with the followers.

Regarding the last (follower) issue, bear in mind that the dimple was added to the original flat metal 1911 mag follower to help retain the last round from being displaced under recoil (when the mag spring was at its least amount of tension for the remaining round).

Another example is how the 3rd gen S&W .45 mag followers have a raised bump on the top (which, being plastic, can be worn through by continued shooting). I've fired enough rounds through any number of 3rd gen .45 mags to have completely worn through that little raised bump and started to experience live-round ejection of the last round. Interestingly enough, it was in the shortest 3rd gen .45 mags, the 6-rd 4513TSW mags, with their lighter & faster cycling slides, that I could start to notice this condition as it developed.

SIG wasn't selling the 938 when I went through their pistol armorer class, so I'd call and discuss the matter with them, first, just to see if they'd been receiving any similar calls (which might be related to a just-recognized mag lip, spring or follower issue).

When you have vendor-supplied parts (mag bodies, springs, followers) being received in substantial quantities (one spring company said they often shipped cases containing 10K springs to a retail vendor customer), and new shipments may get mixed in with existing gun company parts stock, it can become difficult to ID subtle issues like minor spec variations until after the parts have been sold to customers. More's the pity, but there you go.

If the "new" mags you got last month were made with the same parts (production period) as the borrowed "new" mag you tried, it's not impossible for them to possibly have the same issues ... if it's a mag-related issue.

I'd also replace the recoil spring, just because it's easy and can also have an effect upon slide velocity, which can sometimes be involved in this sort of thing.

Call SIG and see what they recommend.

Just my thoughts.

 

[GEM]

I had a brand new Taurus PT-22 that would do that in mid magazine (new ones).

 

[sjybarra]

check your ammo

the load could be wrong. causing the pistol to double tap

 

[astra600]

I had a Ruger P90 & P345 that both did that. Eject a live round with the empty case. Ruger never figured either one out. Both got traded in for different brand new guns. Both were bought new and had less than 200 rounds through them. Four shot semi's are a pain.

 

[Miked7762]

Engaging the slide stop while firing would be hard on the notch on the slide, but shouldn't cause extra rounds to fly out of the magazine, MikeD.

Lateral or downward pressure will keep the magazine follower from feeding the last round correctly and it will behave just like a bad magazine spring or follower.

 

[4v50 Gary]

I'm wondering if you're getting hyper-function? Slide is going back too fast for the magazine.

 

[JWH321]

I do have a 938. I carry it everyday.

I can duplicate what your seeing it by holding my finger on the slide lock when I fire. I think it must keep the round from popping up completely. I suspect it is not the gun.

 

[rskent]

the slide locked to the rear and the gun was empty. I found a live round on the ground each time.

I have seen this happen with other guns from over lubrication. Not saying this is you, but it is something to look at.
Excess lube gets on hands. Lube gets on rounds when loading mags. Lube ends up on magazine feed lips and causes inertia feeds.
Slide locks back, live rounds on ground.

 

[1911Tuner]

Magazine.

Probably a weak spring if it happens on the last round or two. If anywhere in the magazine...probably damaged lips.

The round is jumping the lips when the slide smacks the frame and jerks the pistol up and back violently. The cartridge obeys Newton 1A and tries to stand still while the gun is moving away from it.

 

[Theohazard]

Lateral or downward pressure will keep the magazine follower from feeding the last round correctly and it will behave just like a bad magazine spring or follower.

I do have a 938. I carry it everyday.

I can duplicate what your seeing it by holding my finger on the slide lock when I fire. I think it must keep the round from popping up completely. I suspect it is not the gun.

I'm with these guys. Their explanation makes perfect sense: If your thumb is pressing down on the slide stop while you're shooting, that means the follower won't go all the way up when feeding the last round, which can definitely cause feeding issues on some guns.

 

[oss117]

This is an interesting thread. I had my 938 out to the range last tuesday and encountered the same issue. I was shooting 147 grain loads for the fist time, but was also trying a little different hold where my thumb was reasting atop the safety. I guess i may has also depressed the slide release, but it did lock back on the last round.

 

[PakWaan]

It's not a slide lock issue, as my hands were nowhere near it.

Interesting twist. When this happened a few days ago, I was firing a combination of Gold Dots and Golden Saber - both hollow points, since I had just gotten the gun back from Sig because it wouldn't feed HP ammo. Yesterday, I put 200 rounds of 115 and 124gr FMJ through the gun without it ever happening once. Today, I put 50 trouble free rounds of FMJ through it again, then switched to HPs. Out of 5 magazines of HPs, it happened 3 times, always with the last round. I switched back to FMJ and the problem went away. So it is an issue with HPs only.

 

[rcmodel]

It is a magazine issue.

If normal length FMJ rounds feed.
And shorter JHP squirts out the top?

The mag feed lips are too short, and releasing the shorter rounds before the bullet is stuffed under the barrel hood and held down in line with the chamber so it can chamber.

Call SIG and whine like a whipped dog until they send you some new mags that are made right.

rc

 

[PakWaan]

I talked to Sig today, they want the gun back again, so I'm shipping it off tomorrow along with the magazines. We'll see what they come up with.