I did a test with 4 Shadow 2's. Each had an extended firing pin and an 8.5 lb hammer spring. I left the 8.5 lb hammer spring in, put the original firing pin and firing pin spring back in, and tested them with Blazer 124 gr, Eley Competition 124 gr, Federal Syntech 150 gr, and my handloaded 125 gr (with Federal primers). One gun wouldn't set off one of the Blazers, otherwise everything fired every time. I tried the one cartridge that wouldn't fire in all of the guns, and it wouldn't fire in any of them even after several strikes, so it may have been a defective primer. So, I'll probably err on the side of safety and leave the original firing pins in. If I have problems down the road, I could change my mind, since this would be such a rare occurrence. This is with an 8.5 lb hammer spring so, if you're running a 10 or 11 lb hammer spring, I can't imagine you'll have a problem.