Hammer bounce

[tomme boy]

I was just watching Guns & Ammo ov TV. They were doing a test of the S&W Governor. As they were shooting, they ran a couple of slow mo clips. 2 times it showed the guns hammer coming back about 1/2 way then back down. Is this a problem?

[44man]

All guns do it, even single actions. Normally it is not a problem.
Installing lighter hammer springs will make it worse.
It is caused by internal case pressure against the inside of the primer that kicks the pin back. More head space also will kick the primer out a little before the case is set back.
S&W might have the worst problems with it because the cylinder stop can stay forward from inertia due to the design. That unlocks the cylinder and torque will turn the cylinder backwards. There was a lot of trouble with some 29's where the cylinder turned all the way back and locked up on the first already fired chamber and you would just get a click for the next shot. Hammer bounce still caused no trouble.
But on the X frame, .500 S&W, bounce is severe enough and recoil torgue so strong, the cylinder can rotate back before bounce is over.
If there is a live round in the chamber it goes back to, the gun can double.
The fix is a stronger cylinder stop spring and hammer spring. To be safe, leave the chamber under the hammer empty when you load.
This will start a fire storm of arguments where it will be said the trigger was pulled twice to make the gun double. :groner:
Pictures taken at firing with a chamber marked with a magic marker always showed a backwards rotation with no trigger movement at all.
Recoil management also helps with a strong hold that showed less cylinder movement but a weak shooter can be overcome with torque to get full cylinder rotation clear back to the previous chamber.
I don't know what happens to the hand, you would think it would prevent backwards rotation but it seems it can't. Maybe it needs a stronger spring too.

[Mohillbilly]

There has been a case of a single action Colt , badly worn , go full auto , because of the insert around the fireing pin re cock'n the hammer and happening so fast that the trigger could not be released in time . The person had a death grip as the old gun unloaded it's self .

[44man]

There has been a case of a single action Colt , badly worn , go full auto , because of the insert around the fireing pin re cock'n the hammer and happening so fast that the trigger could not be released in time . The person had a death grip as the old gun unloaded it's self .
Yes, a lot of that was caused by the pin actually punching a hole in the primer. There was a lot of room around the hammer mounted firing pin and that is a lot of gas banging on the hammer.
Some foreign percussion rifles had a large flash hole and the hammer would cock every shot.

[tomme boy]

You could clearly see in the slow motion clip the trigger was all the way bsck the whole time. My little 38spec alum frame snubby does this. I always see a differant strike on the primer on the +P loads than the target loads. The +P looks like they are hit twice. It has never doubled. It it not a gun that I shoot a lot. It gets carried more than anything as it is lite.

[x101airborne]

I am not making light of the problem, and I HAVE had it happen on an old H&R, BUT...... a runaway X frame? Now that would start a forrest fire!

[MtGun44]

I believe I read about an early semiauto prototype that used primer setback to power
the action. As I have previously reported, a friend decades ago fired his first test shot
on all old guns with them in a tire and pulled with a lanyard. When we went up to a "new"
7x57 Rem RB, the hammer was cocked, the block was open and the chamber empty. What
the . . . . . ?? Tried it again, watching closely and saw the case shoot back at very high
velocity as it did the same thing. Firing pin was too long, punctured the prime, gases
pushed the firing pin hard enough to cock the hammer, which unlocks the block, and
residual pressure opened the block and ejected the case smartly - right into your eye if
you were holding it normally and had no safety glasses. Shortening and rounding the
firing pin fixed it.

Lots of weird stuff goes one when a gun fires, very high pressures and inertial forces,
Ya'll be careful out there.

Bill