Sig Sauer Nightmare Fastback Update

The Sig Nightmare Fastback is now at approximately 1700 rounds, and we’re closing in on the finish line. However, it’s begun to develop an unusual tendency to double feed when using Winchester white box ammo. After some testing, I’ve come to the conclusion that this is likely because the WWB has a shorter OAL than all the other types of ammo I’ve used. The question then is should I count these malfunctions against the gun? I’ve not been able to reproduce them with any other brand of ammo.


  1. Winchester has failed me in my Sig 1911 classic stainless. I have found rounds to fat to feed into the chamber, bullets over seated into cases, marked or damage cases. But I still buy it because the value is good and 3 out 10 boxes has maybe 1 or 2 bad rounds. Most of this was when the ammo shortage occurred and makers couldn’t make rounds fast enough. That said I’ll take white box over Remington any day. That stuff burns very dirty and accuracy for me was all over the place. White box just two weeks ago I was getting a 1″ group at 40ft from my 1911. If you are barred from hollow point ammo, I’d argue this is pretty good carry ammo if your gun shoots it.

    1. I only say white box is worth while carry rounds because misdeeds have been small for me compared to rounds shot. I can’t afford to shoot carry ammo enough to qualify more expensive ammo.

  2. I agreee. Check the ammo and if in spec it counts against the gun unless the book says don’t use it.

  3. Would it be possible to have a third party make up some .357 Sig rounds with a couple of projo shapes loaded at various lengths?

    It might be an interesting method to further discover the operational envelope of this gun.

    The Sig is interesting in that it’s a factory 1911 with that chambering, and it makes sense that Sig would be the company to provide such a gun.

    Has there been a discussion of mags for this gun? I may have missed it, I’m curious to see what sometgibg with slightly different geometry, like a Tripp Cobramag, might do.

    Count me in the group that says if it malfs w/ SAAMI-spec, it counts. I’ve previously read that as a relatively modern design, the SAAMI spec for .357 Sig is tighter than most other pistol rounds, and that factory ammo tends to be if higher quality.

    On a ridiculous note, I wonder if a spare barrel in 9×25 Dillon is feasible.

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