I have a fairly new USP, both Buffalo Bore 230 FMJ-FN and 255 Hardcast in 45 Super have had failure to go into battery, the hardcast a little worse. If I do a barrel drop-test into the chamber with the gun broken down, the 45 Super rounds do not fit the chamber properly, they sit above the barrel hood. It appears the bullet (not the casing) is too large to fit. It hits the ledge where the polygonal rifling starts.
I just received some Underwood xtreme penetrator and hardcast rounds also. I drop-tested these but have not yet fired. The hardcast seems like it just might work, nearly flush with the barrel hood. The Xtreme Penetrator sits pretty much like the B.B. rounds did. I may get to the range tomorrow to verify. In the same barrel I have tried 6 different factory .45 ACP rounds and they all fit easily and sit down in the chamber properly. I wish these guys did not oversized their rounds in .45 Super. I can’t go back to HK about chamber Size when all the .45 ACP runs fine.
Anyone want to buy a full box of 230 BB FMJ-FN let me know. Probably 30 rounds of Outdoorsman hardcast I have leftover also that just don’t work in my USP 45. FWIW I also tried drop tests of these same rounds in a couple used HK45c’s at my LGS, looked similar.