This is news to me. I was considering finding a 357sig barrel for my USPc 40. What has to be done to make it work?I have used EFK 1911 stuff and have been satisfied with it, but I have never used a barrel from them. From what I have heard it can be hit or miss with them on barrels and the one area that gives me concern is that they still produce a .357 SIG barrel for the USP knowing full well that the customer is going to drop a fair amount of change on a barrel that is not going to work without further modifications to barrel and magazine. When Jarvis found out that there is nothing that can be done to make the USP work with the .357 SIG without permanent mods to barrel and magazine they quit chambering barrels for the USP in .357 SIG (I know it looks like you can still order them but just try it, they will not take the order).
The fact that EFK is more than willing to take your money on something they know is not going to work makes be look at them with a suspicious eye on all their products, past experience notwithstanding.