SIG-Sauer GSR Revolution Carry. The problems started with the second shot ever fired through it - a nose-down failure to feed. Wilson 47D magazines fixed this, but it still had constant failures to return to battery. I sent it back to Sigarms and they polished the feed ramp. This helped some but did not cure the problem. Then it started failing to extract. The hook broke off the extractor. I sent it back a second time. Then I shot it some more and suddenly noticed the "manhole cover" (a little threaded circular plug in the slide) was missing. Further examination revealed that the firing pin safety plunger in the slide was also missing. I sent it back a third time. They gave me a new one.
The new gun (sans "manhole cover," I noticed) was much better, functioning OK with hardball and Winchester Silvertip, but would not feed any 230-gr. JHPs. The insert in the Novak front night sight went out. And the thumb safety engagement became compromised - the hammer would move forward slightly if I squeezed the trigger with the safety engaged, then, when I thumbed down the safety, the hammer would fall to half cock. Back it went. Through the last 200 rounds it has not had any more problems provided I use the Wilson magazines - BUT - if anything else breaks I am going to declare "enough is enough."
I will give Sigarms credit for replacing the first gun without my having to hassle them, as well as for sending me prepaid shipping labels for all the repairs except the first one.