I don't have any blow back issues with my Revolution. I only shoot 100 grains of 777 though. I don't feel a need for more powder than that. The firing pin is a rebounding type set into the breech block. The hammer is internal and is part of the fire control mechanism. It's all enclosed in the trigger group. It's an ingenius little design. Cayugad, you are right, it has a Green Mountain barrel and it's extremely accurate! I have shot sub 1" groups (3 shot) @ 100 yds. using 300 grain Hornady SST's.