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.