Lyman’s GPR hammer needs adjusting

[timetraveler]

Hello all, first post. I have an older GPR and the hammer doesn’t come down on the cap cleanly. It needs to be moved forward or bent open a little. Right now the front rim of the hammer hits the cap first but the hammer force pushes it the rest of the way down. The gun fires fine but I’d like to fix it but don’t know if it’s possible. Can a gunsmith heat the hammer and bend it open a touch? I don’t see any other way. I saw an offset nipple but the threads were different. Anyone have a suggestion? Should I dremel the front rim off so it doesn’t skip off it? Don’t really like that solution either. I got to say the gun is a shooter, I’d like to fix it.
Thanks, glad I signed up. I actually did years ago but never posted and when I tried to sign in it wouldn’t let me.

 

[TechMoron]

Something as simple as a shorter nipple might solve your problem. I personally would not dremel open the hammer cup.

 

[timetraveler]

I thought of that too but found it doesn’t help. I’ll try to post pics later today or tomorrow, got a busy day today and tonight

 

[French Colonial]

Without pictures it is hard to diagnose but I agree with TechMoron, a shorter nipple may do it.
I have had good luck with heating and bending the hammer when needed as well.

 

[Grenadier1758]

Yes, @timetraveler, the hammer can be heated and bent to properly clear the nipple for a solid strike. This was often a necessity for CVA hammers in the kits sold in the 1970's. The whole rifle needs to be used as the test fixture when bending the hammer to be sure the cup is centered on the nipple.

 

[timetraveler]

Thank you guys, that’s what I wanted to know. Don’t know if I should do it myself though. I’ll ask a gunsmith I heard about.
Thanks again

 

[timetraveler]

I bought my GPR as a kit, I think from Dixie Gun Works sometime around 1970

 

[timetraveler]

I’m mean late 80’s or early 1990

 

[yotyfox]

Try unthreading the nipple 3-4 turns to make it longer and let the hammer down (without a cap) on it to see where it hits and see if it's worse or better. That way you can see if a shorter or longer nipple may work. A longer or shorter nipple may fix your problem depending on the arc travel of the hammer.

 

[snakebit]

A lot of good advice ^. Now for my 2¢. Dremel's and guns shouldn't even be in the same room at the same time (removes the temptation).

 

[timetraveler]

No, longer or shorter nipple won’t work. When I started trying to solve this problem that was the first thing I looked at.
Then I thought maybe moving the whole lock set, trigger assembly forward or just the hammer forward but everything is such a tight fit I don’t think that’s possible either, But, I haven’t taken anything apart yet to know for sure.
Can you still get replacement parts for the GPR still? What if the gunsmith wrecks my hammer. Maybe I need a blacksmith

 

[oldramrod]

Yes, @timetraveler, the hammer can be heated and bent to properly clear the nipple for a solid strike. This was often a necessity for CVA hammers in the kits sold in the 1970's. The whole rifle needs to be used as the test fixture when bending the hammer to be sure the cup is centered on the nipple.

Back in the late 70's and early eighties I assembled several CVA kits for the local Amish boys and almost every one needed the hammer aligned with the nipple. I used a map gas torch to heat the hammer in the area to bend and then bent it placing a box end wrench over the hammer, Then when I had it aligned I sprayed it with WD40 while it was still hot to give it a nice Color bluing .Some times I had to square up the hammer face to the nipple. I would do this by placing a thin brass spacer in the hammer after "tinning" the hammer with solder, setting the tinned hammer with the spacer on the nipple and heating it with a common propane touch enough to melt the solder, Then let cool . You have to be careful and not have too much solder in the hammer

 

[timetraveler]

Back in the late 70's and early eighties I assembled several CVA kits for the local Amish boys and almost every one needed the hammer aligned with the nipple. I used a map gas torch to heat the hammer in the area to bend and then bent it placing a box end wrench over the hammer, Then when I had it aligned I sprayed it with WD40 while it was still hot to give it a nice Color bluing .Some times I had to square up the hammer face to the nipple. I would do this by placing a thin brass spacer in the hammer after "tinning" the hammer with solder, setting the tinned hammer with the spacer on the nipple and heating it with a common propane touch enough to melt the solder, Then let cool . You have to be careful and not have too much solder in the hammer

Wow, I don’t know if I trust myself to do that. I would love to try it though. You want to do mine ?
Thanks for the post though, that was interesting.
I still have to make some calls see if I can find someone. If I can get another hammer I may try it but not yet.
I saw another thread about how to age your GPR and apparently mine was made in 1999. I thought it was older than that but I was mistaken.

 

[timetraveler]

Here’s one reason I’d like to fix it.
I took it out to sight it in for this years muzzleloading season and after messing with the windage and elevation a little bit here’s what I got at 50 yards with a PRB.
I don’t know if this is common for you guys shooting BP but I can’t believe how accurate it is.
Here’s my first 3 shots
then my final 3.

 

[timetraveler]

I can’t ask for better than that.

 

[timetraveler]

 

[Indy Durtdigger]

No, longer or shorter nipple won’t work. When I started trying to solve this problem that was the first thing I looked at.
Then I thought maybe moving the whole lock set, trigger assembly forward or just the hammer forward but everything is such a tight fit I don’t think that’s possible either, But, I haven’t taken anything apart yet to know for sure.
Can you still get replacement parts for the GPR still? What if the gunsmith wrecks my hammer. Maybe I need a blacksmith

But have you tried a longer or shorter nipple . Couldn't help myself, a-lot of folks on here post without reading but mean well all the same. The guys that recommended heating and bending the hammer get my vote just make sure it is striking the nipple square when done, that's when a different height one may come in handy as a bend one way often requires an adjustment another way.
Investarms made the Lyman GPR and still makes the same rifle as the Gemmer Hawken under their own name so replacement locks, barrels, and whatever parts can be sourced from various suppliers when they have them.

Also, heating the hammer may well do something to the finish on it. Some cold blue of some sort wouldn't hurt. The Brownells OXPHO blue is kinda darker like the finish on my GPR. May not be exact but close.

This is getting wordy but something else popped in the old noggin. You might check the adjustment on the tang and breach hook via the forward tang screw. There is or was a video on You Tube from Lyman showing the correct procedure and I've posted it here before. If that interface isn't correct, it could have an effect on how the hammer relates to the nipple on the bolster. And the adjustment can be tweaked a just tad to affect it with no other ill effect.

 

[#BPBReloadingFFL]

So we get pictures of targets,gun and picnic table. Stil no picture of the lock & hammer on the nipple.

 

[timetraveler]

Here are some pics I just took.
It doesn’t happen all the time but a little bit of cold contracts the hammer another 1/16 or so then the lip skips off the cap.
Right now it clears

 

[Indy Durtdigger]

Here are some pics I just took.
It doesn’t happen all the time but a little bit of cold contracts the hammer another 1/16 or so then the lip skips off the cap.
Right now it clears
View attachment 369842View attachment 369843View attachment 369845

Since that's hitting the leading edge most definitely check that adjustment before doing anything else. I'll see if I can find that vid again.