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Firing pin hole drilled off-center - how to fix?

Shinbone

Hi All,

I, myself, am not a gunsmith, but I need some guidance on what to do about a firing pin hole that was drilled off-center during manufacture. The maker is out of business, so a return to the factory is not an option. I bought the gun used on g-broker, and have not shot it yet, so I can't say how well it currently shoots. I have a second rifle from the same maker with the same problem, so if I can find a solution, I'd fix the second gun, too.

As the photos below indicate, the firing pin hole is about .015" off-center with reference to the OD of the bolt body. (I know the caliper looks a little crooked in the photos, but I have carefully done this measurement *multiple* times hoping it is just operator error I am seeing, but I always get the same off-center result). My original plan for this rifle was to have a smith do a full action truing and custom barrel to turn it into an excellent shooter, but, now, I am worried the off-center firing pin hole will always limit the accuracy, and thus any custom accuracy work will be a waste of resources.

A couple of well-respected gunsmiths have looked at this problem, and opined the off-center hole will negatively affect accuracy, and, unfortunately, a repair would be too difficult to be worth the cost. Best to just accept that the gun will be accurate enough for hunting and forget about ever getting gilt-edge accuracy from it.

Any idea on how much this will affect accuracy? Any suggestions on how to fix it?







TIA
 
When I was alerted to this problem, my thought, too, was "we are going to bush the firing pin hole, so what is the problem?" But, both of the aforementioned gunsmiths turned down the bushed firing pin option because "the original firing pinhole is off-center, and bushing it would result in a still-off-center hole, just narrower."

Both of these guys have bushed a lot of firing pin holes, meaning they do have considerable experience in the procedure, so I do believe them when the say a standard bushing job won't address the problem. But, I don't know, I am just repeating what I am being told by folks who know way more than I do . . . ?

I don't yet have any spent brass from this gun, so I can't say whether the primer strike is in the center of the primer.
 
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Couple things...get an empty but primed case in the chamber, fire it and see where the indent is. If it does need to be bushed, a plug fitted to the bolt face is normally done.
What actions are these? Pretty sure I know..... ;) -Al
 
An oversized bushing, like used to repair primer blow by, should take care of it, no matter what diameter FP hole is used.
 
If the firing pin hole is off-center, does that mean the other portions of the hole through the bolt are also off-center?

Maybe someone can steer me towards an explanation, or video, or cut-away image of bushing a firing pin hole so I have a better understanding of what that means?
 
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So you haven’t even shot the rifle yet and you are worried about .015” off center firing pin hole affecting accuracy? It’s a controlled round feed bolt. Not a precision benchrest action. You’d be wasting more time and money trying to fix that for no gain than you would anything else.

Go shoot the rifle then come back and talk to us if there’s issues. Sorry if I sound a little harsh but come on, think about how silly that is. You could bush and straighten the hole and not be any better off with a CR hunting rifle. Just have less money in your bank account. As long as the whole firing pin raceway is traveling straight thru the bolt face hole then I wouldn’t worry about .015” off.
 
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LS - I am not complaining. I am just reporting on an issue that was serious to enough to stop work on a project, and asking for thoughts and suggestions by folks more knowledgeable than me. And, I am sure at least one person has dealt with this issue before, and there is no sense in me re-inventing the wheel.

If I run factory ammo through this gun and get, say, 1-1/2" groups - what does that tell me about the effects of the concentricity of the FPH?

If I take the time and expense to develop a hand load for this gun and get, say, 1" groups - what does that tell me about the same question?

Unless the gun is wildly off, or amazingly accurate, such shooting exercises will be inconclusive, is my guess.
 
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Shinbone said:
LS - I am not complaining. I am just reporting on an issue that was serious to enough to stop work on a project, and asking for thoughts and suggestions by folks more knowledgeable than.
Click to expand...
CR hunting rifles are crude objects with loose tolerances built into them that allow for very good reliability. Which is needed when hunting dangerous game. So .015” off center on something in a rifle like that is really nothing. That’s less than 1/64”

And how do you know that the bolt body is not “out of round”? Has it been turned on center with a runout indicator? The bolt being out of round is the more obvious explanation.

Picking a CR action apart like you are gonna use it for 1K BR competition is pointless. I see no reason to worry about that at the moment. If you shoot it and strikes are way off center and having ignition issues then that could be addressed. But I bet you find there’s absolutely nothing wrong with it
 
But to bush that bolt it would need a deep bushing not the shallow ones normally done just to address primer blanking. It doesnt matter if the hole is off center or not even there, the whole hole will be replaced. Having the tools to hold that bolt is probably the main issue with finding somebody to fix it. Im guessing it wont be an issue though so go ahead with it is my opinion.
 
Shinbone said:
When I was alerted to this problem, my thought, too, was "we are going to bush the firing pin hole, so what is the problem?" But, both of the aforementioned gunsmiths turned down the bushed firing pin option because "the original firing pinhole is off-center, and bushing it would result in a still-off-center hole, just narrower."

Both of these guys have bushed a lot of firing pin holes, meaning they do have considerable experience in the procedure, so I do believe them when the say a standard bushing job won't address the problem. But, I don't know, I am just repeating what I am being told by folks who know way more than I do . . . ?

I don't yet have any spent brass from this gun, so I can't say whether the primer strike is in the center of the primer.
Click to expand...
Young feller, you said you trusted the smiths that said it can't be done, so why bother the guys on this forum?
 
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First fire a round or two, just with primer in the case and see where it strikes and it does fire or not. If they fire and pin hit is in center or very close to it on the primer strike, then don't worry about it.
If it does not work or is so far off you just don't want it, like that.
Then contact Carlsbad and see what it says. If it does need work, he can do it and get it correct.
 
You better not buy a borescope! :oops: Shoot the gun and see how it does. It might shoot great as it is. How will you know if any custom work makes it better if you have no base line for the gun?
What is the manufacturer?
Just putting a new barrel on it might give you “stellar accuracy”.
 
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butchlambert said:
Young feller, you said you trusted them smiths that said it can't be done, so why bother the guys on this forum?
Click to expand...
If this thread is a bother to you, then just move on to another thread. Why do you need help figuring that out?

Wait, don't answer that question. Just move along. Thanks.
 
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