HKPRO Forums banner

1 - 3 of 3 Posts

·
Registered
Joined
·
220 Posts
Discussion Starter #1
For some reason I can't figure this out and need your input. I have both a USC and a UMP bolt. My question lies in the operation of the hammer and firing pin assy. The rear of the bolt and the rear of the firing pin assy appear to be flush on both bolts. What causes the firing pin to travel forward?
It appears that the hammer would not even touch the pin assy.

Thanks for your input!
TC
 

·
Premium Member
Joined
·
8,632 Posts
Are you comparing them OUT of the receiver?

You'll need to slide them into the receiver to notice. The ejector - the long thin metal strip that attaches to the chamber end of the barrel - also fits into a slot on the side of the bolt. When the bolt is pushed fully forwards, the firing pin will protrude out past the back of the bolt, but still by just a tiny bit - like 1/16" of an inch or less.

It still doesn't extend past the tab on the bottom of the bolt, however. But... the hammer doesn't look like it hits flat against the back of the bolt either. It appears that the hammer smacks the back of the firing pin at a slight angle forwards (and there is also an angle on the top of the firing pin, probably for the same reason.) The firing pin is not pushed into the primer by the hammer. Instead, it flies forward with enough speed that it is no longer in contact with the hammer face, and dents the primer. Then gun go boom!

Also, if you're playing with it out of the receiver, you can't push the firing pin forward enough to extend past the bolt face unless you push the locking lever at the back of the bolt towards the outside first.
 

·
Registered
Joined
·
220 Posts
Discussion Starter #3
AviatorDave......Thanks!!!!!

I just mocked it up with a barrel, bolt and ejector. Now I see your points exactly. Thanks again.

TC
 
1 - 3 of 3 Posts
Top