Have a new Sig 1911 Nightmare - 5" - 357 Sig. Many times on last round the pistol will fire and the slide will lock back but the empty case is wedged between the barrel hood and magazine. The slide is not up against the empty case. The case is wedged in to the magazine so tightly that the magazine can't be released and the empty has to be pried out. Never seen this on a 1911.

Interesting.

Is it wedged against the feed lips or the follower? Maybe extractor/ejector need tuning?

Does it happen with the same mags? If you don't mark your mags, it's a good idea. If it only happens on certain mags, it's probably a mag issue. If on all mags, either gun or ammo.

What brands of ammo? If more than one, does it happen with all of the brands?

How many rounds through the gun? Sometimes it can just be a break-in issue.

With problems like this it's a good idea to keep a log. Note the details with each malfunction.

I'd also check the barrel ramp, ejector, extractor and breech face for any burrs or irregularities.

Look at the fired cases for any odd marks. If you have to, mark a spot on the case before firing. Load the mag with the marks pointed up. When the malfunction occurs, check the orientation of the cartridge. Might tell you something.

Since it appears to be a problem on only the last round, it is somehow related to lack of a cartridge (in the mag) underneath the fired case. Hard to tell by remote control. The more detailed info you provide, the better responses you'll get.

Welcome to the forum.

about 300 rounds through the pistol. Happens on Winchester white box the most. Have only tried the same magazine. The case jams into the feed lips and against the follower.Case is damage where it wedges into the barrel hood. Has an external extractor - should not need adjustment.
I will try another magazine and different ammo. Thanks for the suggestions. I have checked the breech face - smooth. Barrel hood and chamber good. I agree - it has something to do with no round to support empty during extraction.

Thanks for the info. Good luck. Let us know what happens.

FWIW, WWB has been know to cause problems. However, can't say if it has anything to do with yours.

I've been a chrono (oh, no!) officer of some major matches for USPSA, amd WWB has been notoriously weak in many of its offerings.

.45 ACP 230 grn rn WWB however, is crazy hot. Like 195-200 PF (870 FPS) from a 5" SW 625 revolver and govt size 1911.

I'd try some offerings by other major manufacturers and at least one other mag to see if you can eliminate those as the cause.

Think I found the problem. Comparing the magazine I use with a new one, dimensions of feed lips were the same. However, I noticed the follower of the questionable magazine sort of "nose dived" when depressed. I disassembled the magazine and found the spring was in upside down. One end has a closed loop that is supposed to ride against the follower.Reassembled the magazine correctly and could immediately see a difference. Don't know if it came from the factory that way or if I had disassembled it at sometime for cleaning. Don't remember. I will get to the range next week to try it out. Thanks to all for your suggestions.

Cool! Free easy fixes are always the best. I hope it resolves the issue- I'd still try some other ammo brands to make sure they all work well also.

yep - love the free bees kind. I hope to get to the range tomorrow. Will post my results.
And as Nipper mentioned, I do keep logs on all of my pistols. Good for trouble shooting problems and for general maintenance. On my carry pistols I mark the magazine that have proven reliable.
Thanks again for lending an ear and all of the suggestions.

Thanks for the update. It's always good to learn the outcome of these problems.

Went to the range this morning - no problems - ran like I expect a Sig to run. So it seems the backward spring was the problem. Thanks again for all the help.

Excellent! Thank you for clearing the issue, and enjoy that gun!!!

Thanks Mooney - it is quickly becoming one of my favorite pistols. I really like the 357 Sig cartridge.