Bent brass on extraction

bent as in case mouth? or bent as in case head?

case mouth is normal. probably from hitting the floor. Mine are always dinged a bit from hitting the concrete
case head sounds like an issue to me. maybe extractor.

Case mouth ding is normal. If you reload, sending the case through the sizing die will iron it out.

1911s seem to do that worse than others. Seems to be that there is a fair bit of pressure from the extractor pulling the hot case against the chamber as it comes out, enough to ripple the casemouth. I have caught brass in my shirt that did the same. It's not you, it's the gun, but not necessarily a problem with the gun.

My antique 1911A1 does this at least 90% of the time, just nature of the beast IMHO.

I had that problem with my 1911 Colt 70 series. I replaced the original ejector with a Wilson extended ejector and the problem was cured. It starts the empty out of the chamber a fraction of a second quicker than the original...........Robin

Normal.
The dent is caused by the empty doing a back flip out of the port when it hits the ejector.

Then the case mouth slams into the slide behind the ejection port.

Look on the slide and you will find brass tracks on the slide where the hit it.

rc

Generally this only happens with older 1911's without the flared, enlarged ejection port. I'm a little surprised that the Sig is doing it.

Flaring and lowering the port helps as does tuning the extractor and ejector to get along better. The case dents aren't really a big deal as long as they are all making it out of the port every time.

I have a Sig "Fastback" (same as your Nightmare, but all black, without silver highlights). Mine isn't doing that, so you might play with the ejector a bit - maybe the extended one from Wilson will fix the problem, or maybe the extractor is grabbing the rim a bit too tightly, or a combination.

I wouldn't worry about it unless they're so badly bent that a sizing die doesn't fix it. That would be rare.

It seems that folks are afraid to reuse dented cases.
I get a lot of free brass thanks to that.