Gunsmithing Firing pin question

[carbonbased]

The basic question is: is ok/safe to very lightly sand the circumference of the end of a firing pin for firing pin hole clearance? (Not sanding the end of the pin, just the circumference)

The longer backstory is: I have a new Tikka Super Varmint in 223. Took it out this week and noticed in 23°F weather I was getting light strikes on M855 during initial sight-in, but not on Federal Tactical Tru 77gr when shooting for groups.

Chocking it up to factory grease in the firing pin assembly, I followed the degreasing tips in this video:


My bolt needed SIGNIFICANT force to both remove the firing pin and to actuate it up/down to pump out the grease (both shown in the video). The video guy didn’t have much trouble. Had to use a Knipex smooth-jawed pliers wrench to gain some purchase.

I also didn’t notice really any grease coming out of the FP assembly? Just a trace.

Ok, so now the firing pin and bolt are totally degreased except for a trace amount of grease I added behind the lugs and on the firing pin ramp.

I go out shooting today. Changed scope rings too.

Don’t have anymore M855, but substituted Winchester M193 for the initial sight-in. And got even more light strikes! No problems with strikes later on FGMM 69gr.

And towards the end of the session the bolt became fairly hard to cycle even when just dry firing. Like, I couldn’t cycle it without holding the rifle down on the bench. Otherwise as I’d lift the whole gun up.

Confused, I went home and disassembled the bolt again. It was even harder to get apart than before. To actuate the FP up/down I now had to use TWO Knipex smooth-jawed plier-wrenches; the thing was a bitch!

I was looking for little burrs at the non-FP end, where I had previously used that smooth pliers. I found a couple tiny burrs and used 400grit wet/dry sandpaper to very, very lightly buff those out. No difference. Added a little more winter grease. No difference. Bolt in gun is still super hard to cycle when dry-firing (but cycles fine when not pulling trigger).

After disassembling again, I slowly moved the FP assembly in and out of the bolt and discovered that the culprit was the head of the firing pin. It was grinding as it went in-out of the FP hole.

So, using the same wet/dry 400grit sandpaper, I wrapped it around the circumference of the end of the FP with my fingers and rotated it around so I would take (hopefully) even amounts of material off. I did this very incrementally so not to over do it, and I’d reassemble often to test.

Finally I got to the point where it the FP went in/out of its hole pretty smoothly (still a little gritty). But the assembled bolt cycled great, just like it did out of the box with its factory grease.

One note: I mainly sanded around the FP, or 90° to the long dimension with a twisting motion. At the very end I did do a little sanding parallel to the long dimension as it seemed to ease the gritty feeling more.

My theories are:

A)

1. Gun had no firing pin issue, but had a grease issue in cold weather.
2. My disassembly messed up the head of the firing pin (I was pushing the FP assembly hard, up/down, with the FP head cushioned into soft wood.

Or B)

1. Gun did have a FP clearance issue, but factory grease largely masked it, only showing a few light strikes on M855. When degreased, the bolt showed its true colors with lots of light strikes on M193 plus very hard bolt lift.

Or, I suppose, C)

1. Some evil combo of A and B.

ANYWAY, I am a little paranoid and want to be sure I didn’t do something wrong and wind up with a broken firing pin through my head. If I didn’t do anything wrong, I might sand the pin a bit more so it glides through its hole.

 

[Threadcutter308]

Since you've already sanded it, it's kind of an academic question now......

I would have been inclined to contact Tikka before doing anything and potentially sent it back to them for service/repair. It sounds like it wasn't right from the factory. In that regard, I think it WAS their responsibilty to make it right. But, you've already "modified" it and possibly voided any warranty service that you may have had.

I'm not going to say it is or is not OK to sand the firing pin. Remember, if someone here says it's "OK" and you have a problem, you aren't going to have much, if any recourse because you solicited (and took) advice from an internet forum (as opposed to an established "professional" gunsmith or the Tikka factory themselves).

 

[hlee]

Is the gun going to explode because you very lightly sanded the firing pin? Probably not.

Is the firing pin going to fail because you very lightly sanded the firing pin? Probably not.

Does this sound like it was a warranty repair scenario? Yes.

Is there anything to do other than take the gun to the range and shoot it? Beyond sourcing a factory fresh firing pin, no, not really.

 

[whatsupdoc]

You are fine, some would have you believe that the factory repair personnel are mater gunsmiths and for the most part they are not.

The factory service center most likley would have repaired it the same way except they would have probably used a file to get finished faster.

 

[FisherT&C]

Sounds like there could be a burr in the FP hole on the bolt left by drilling it in manufacturing. That usually can be fixed with the correct size carbide reamer. Too much FP clearance can cause primer flow into the hole and possibly rupture. I wouldn't sand it anymore, if there is a burr in the bolt it will continue to cause problems. Eventually it can sharpen the firing pin and pierce primers. I'm not surprised the Federals didn't have a problem, they are one of the easiest primers to ignite. The military grade primers tend to have a thicker cup.

 

[Freebore221]

Maybe stop shooting 5.56 ammo in your .223 Remington chamber rifle?
Probably where your hard bolt lift is coming from and light strikes on hard primers, most likely nothing wrong with your gun other than operator error in ammo selection...

 

[carbonbased]

Maybe stop shooting 5.56 ammo in your .223 Remington chamber rifle?
Probably where your hard bolt lift is coming from and light strikes on hard primers, most likely nothing wrong with your gun other than operator error in ammo selection...

Ah yes, thanks for the reminder. Previously I have had only 223 Wylde chambers where it was safe to shoot both calibers. The Tikka isn’t marked “.223 only” but it’s probably safer to just shoot 223, dangit.

However, perhaps you missed the part the the hard bolt lift also occurred during dry firing? And maybe I wasn’t clear, the hard lift happened regardless of ammo I used.

 

[carbonbased]

I would have been inclined to contact Tikka before doing anything and potentially sent it back to them for service/repair.

Does this sound like it was a warranty repair scenario? Yes.

I should have mentioned that I only did this because the local shop I use adds a lifetime warranty on any gun they sell, and they deal with the manufacturers and ship it if need be.

I’ve needed that service once. It was awesome not to have to pay $50 shipping and deal with a potentially reluctant manufacturer…I got a new replacement rifle out of that experience!

Anyway, I’ve got a good working relationship with them and bought a lot of guns & suppressors through their shop. I’m glad you guys called this out because I too am always confused when someone modifies a gun that is under warranty…this is one of those exceptions, I guess.

Otherwise, I would not have messed with the gun and would have promptly called Tikka.

 

[Threadcutter308]

I should have mentioned that I only did this because the local shop I use adds a lifetime warranty on any gun they sell, and they deal with the manufacturers and ship it if need be.

I’ve needed that service once. It was awesome not to have to pay $50 shipping and deal with a potentially reluctant manufacturer…I got a new replacement rifle out of that experience!

Anyway, I’ve got a good working relationship with them and bought a lot of guns & suppressors through their shop. I’m glad you guys called this out because I too am always confused when someone modifies a gun that is under warranty…this is one of those exceptions, I guess.

Otherwise, I would not have messed with the gun and would have promptly called Tikka.

I don't have any dog in this hunt, I'm just asking questions and not trying to be inflammatory..........

I understand what you are saying about your gunshop. Sounds like a cool (lifetime warranty) deal. However, I would also assume that the cool deal warranty is void if a customer starts "troubleshooting" and modifying the firearm in question, on their own. If I'm wrong and the gun shop has no problem with you making modifications, then all the "better". (Right up until the point where something has been modified, it (the firearm) fails and injures/kills someone). Then, I'd bet they'd have a big problem with it, particularly if someone had gotten hurt.

I'd politely suggest that you may be making assumptions based on not entirely understanding the gunshop's (or the manufacturer's) warranty conditions.

Remember, you're (you, me, everyone) are just one fuck up away from catastrophe. A person has to always be extremely diligent/careful to keep the odds in his favor as much as possible.

A couple of other guys have made some very valid points above. I'd suggest re-reading their posts, digesting the points a little bit, then calling Tikka and explain the situation/problem. Then, let (Tikka) them tell you how they are going to handle things.

As a point of reference, I am an AMATEUR gunsmith. I only work on guns for myself. I do not/will not work on anyone else's firearms for free or for pay. I do a pretty good job of knowing my limitations and I will not risk my own safety or anyone else's safety by doing something (a "repair") if I even remotely believe I'm in over my head. Have I been there before ? Yes, most certainly. And I still have both eyes and all 12 10 fingers to prove it.

Having said that, had I been in your shoes way back in the beginning, I would have called Tikka first thing (before ever picking up a tool/sandpaper) and asked them to fix the problem. The primary reason ? To keep the warranty intact and in good standing. Then, if something were to happen, the ambulance chasers can't point the finger back at you.

Good luck with whatever you do. I don't think you've done irreparable harm, but I'd suggest stopping what you have been doing and just call Tikka.

 

[carbonbased]

I don't have any dog in this hunt, I'm just asking questions and not trying to be inflammatory..........

I understand what you are saying about your gunshop. Sounds like a cool (lifetime warranty) deal. However, I would also assume that the cool deal warranty is void if a customer starts "troubleshooting" and modifying the firearm in question, on their own. If I'm wrong and the gun shop has no problem with you making modifications, then all the "better". (Right up until the point where something has been modified, it (the firearm) fails and injures/kills someone). Then, I'd bet they'd have a big problem with it, particularly if someone had gotten hurt.

I'd politely suggest that you may be making assumptions based on not entirely understanding the gunshop's (or the manufacturer's) warranty conditions.

Remember, you're (you, me, everyone) are just one fuck up away from catastrophe. A person has to always be extremely diligent/careful to keep the odds in his favor as much as possible.

A couple of other guys have made some very valid points above. I'd suggest re-reading their posts, digesting the points a little bit, then calling Tikka and explain the situation/problem. Then, let (Tikka) them tell you how they are going to handle things.

As a point of reference, I am an AMATEUR gunsmith. I only work on guns for myself. I do not/will not work on anyone else's firearms for free or for pay. I do a pretty good job of knowing my limitations and I will not risk my own safety or anyone else's safety by doing something (a "repair") if I even remotely believe I'm in over my head. Have I been there before ? Yes, most certainly. And I still have both eyes and all 12 10 fingers to prove it.

Having said that, had I been in your shoes way back in the beginning, I would have called Tikka first thing (before ever picking up a tool/sandpaper) and asked them to fix the problem. The primary reason ? To keep the warranty intact and in good standing. Then, if something were to happen, the ambulance chasers can't point the finger back at you.

Good luck with whatever you do. I don't think you've done irreparable harm, but I'd suggest stopping what you have been doing and just call Tikka.

Oh yeah, totally stopping. Not going to shoot it, even, but I’ll haul it into the gun shop. It was one of those “in the heat of the moment” sort of deals, you know? Like wtf is this stupid gun not working? Gunna make it work! Lol

I don’t usually ever do that sort of thing. But I’m getting tired of new guns having issues.

I unpacked the cheap borescope I just bought and snapped some pics. The burr in the firing pin hole was the correct diagnosis, I think. These are pics off of the borescope’s display, btw. Don’t feel like digging out my mini-sd card reader.

You might wonder how I took those pics. I was scratching my head too as to how to accomplish it. Maybe this will help someone later.

I laid the bolt on a table and took the mirror off the scope, then placed the scope on a rubberized pen. The scope is right in front of the FP hole where the bullet would be.

Then I used a low-power penlight to illuminate the FP hole from behind, through the bolt body. The light is not close to the hole, but is at the far end.

Thx @FisherT&C for the idea to look in the FP hole!

 

[Freebore221]

Hard bolt lift regardless of ammo used or dry firing may be the result of shooting the higher pressure 5.56 ammo in the .223 Rem chamber. Are your bolt lugs looking ok? Might be galled or otherwise damaged?

Best of luck to you sorting it out!