GPR lock

[28659]

Took my new gpr to the range today for the first time.
got 4 shots off and then gave up. The Percussion lock keeps
stopping at half cock. I take the lock out and operate it by hand and it works ok. Put it back in and it shoots one round, then
stops at half cock again. Any body have any ideas on whats
wrong?

 

[Zonie]

My GPR did the same thing when I got it.
I should mention that I bought it "used" and I strongly suspect the former owner was to blame however the fact remained. It hung up at half cock.

The problem was the fly was missing from the tumbler.
The fly is a tiny little part that fits into the tumbler and blocks off the half cock notch from the tip of the sear while the hammer is falling.
It is so small it is easily lost (or broken) and without it, the sear will re-engage the notch when the gun is fired.
You can get one by following this link. It is under "Percussion Lock Assembly" or "Flint Lock Assembly"
[url] http://www.lymanproducts.com/store/page155.html[/url]

I ordered a replacement from Lyman and had it in less than a week.
I should point out that when I installed the fly, it didn't work like it should until I stoned the little point that rides on the sear nose down a tiny little bit but it now works just fine.

I wouldn't recommend shooting your gun until you get this fixed.
Repeated hang ups like you describe can (and will) break off the nose of the sear or the shoulder of the half cock notch.

zonie

 

What Zonie said, but also if the fly is there(it's really only the size of a knat) it sits between the tumbler,and lockplate on most but not all locks, but is also sometimes between the tumbler, and bridel, it could be sticking because of fouling or grease. a lot of times new guns come with way too much preservitive grease in the lock, and they need to be cleaned and properly lubed. I know the barrels on Lymans are famous for this. Gunscrubber or spray brake cleaner and a brush will work without having to take the lock apart. As Zonie said that little fly is very, very, very, let me repeat that very easy to lose. I've donated my share to the floor gods on more than one ocasion, so if you choose to disassemble be very careful. Bill

 

[28659]

there is a fly in there and it seems to work oki when i hold
the lock in my hand and operate it. I will try the brake cleaner
and see of that works. thanks

 

[AZ-Robert]

Could it be rubbing or binding against wood when installed?

 

[Pork Chop]

I have a pistol that will do the same thing if the lock mounting screws are too tight. If it all works OK in hand, put it back in, but only snug up the screws - don't torque them down.

 

[2172]

I had the same problem with my GPR...there is at least one thread from a year or two ago with a number of solutions...what worked for me, in addition to doing all that has been suggested here, was to take a coil off the sear spring...
others have tried that with the problem and say it works for them too..if all of the good ideas on here don't work, try that...Hank

 

[28659]

I have it working good now. I cleaned it real good with
solvent. Been dry firing it on a faucet washer and it seems
to be ok. Thanks for all the help!

 

[CrackStock]

You may have overtightened the lock bolt. This can cause the lock parts to be pulled against the wood and bind. It needs to be just snug enough so that powder does not fall into the lock opening, but otherwise, tightness is not important.

CS