Gunsmithing Is a fire checked bolt a safety concern?

[Vicdiesel]

As stated in the title, is there a safety issue with my bolt?
I bought a second hand AI AXMC and upon receiving the rifle I found the bolt to have quite a bit of fire checking. It looks to have been bushed (after the initial fire checking I believe) so I don’t expect anymore issues with it.

Thanks guys!

 

[Deleted member 10043]

I don't even know what fire checking is on a bolt.

 

[Vicdiesel]

Here is an example on an ar bolt.
Mine is a bolt action. It has happened to me due to soft primers. Can also be caused by excess pressure.

I don’t know what caused it on my newly acquired rifle.

 

[pmclaine]

Just about every bolt I own sadly has some of that gas plasma cutting evident.

Winchester primers a few years ago matched with FGMM brass has been my cause.

Safe or not I cant say.

I shoot all my rifles though.

Your AR bolt is way beyond anything my rifles evidence of the problem.

If your AI has one or two pits I cant see it being an issue.

 

[Vicdiesel]

that is not my bolt, it was just a google pic. I was showing culpeper an example.
I"ll take a pic of my bolt this afternoon. it is rather extensive and deep checking

 

[smoothy8500]

Just about every bolt I own sadly has some of that gas plasma cutting evident.

Winchester primers a few years ago

Same here, all my bolts present a lot of pitting due to their leaky primers. Not an issue other than cosmetic.

 

[spife7980]

None of my bolts have that. Its not good but its not catastrophic either. You should be able to continue to use it just fine but Ill wait for a pic before any real opinion can be given.

Dont load so hot and dont load loose pockets and you wont have the issue guys.
And dont shoot high pressure small primers on large firing pins which only exacerbates the issue.

 

[Vicdiesel]

Found a pic...

 

[FUNCTIONAL]

it may be the way the picture comes across but those look pretty deep and pronounced, almost like a punch hit it. I'm use to seeing it more like erosion than what you have there.

 

[Supersubes]

I always have to wonder how the shooter/reloader just lets that go and doesn’t see a problem. I have a friend who did that with one of his guns(shame on you James, you’re better than that!). If the primer just falls into the pocket, drop both into a trash can and move on. Then evaluate how you’re killing primer pockets and work to avoid it.



OP, none of that is directed at you of course. That bolt head is interchangeable, and can be swapped out for a new one by Mile High. That bolt doesn’t look bushed to me, but I could be wrong. Remove the striker assembly and put your caliper on the tip of the firing pin, if its .080” or so, what you have is all factory.

 

[pmclaine]

Same here, all my bolts present a lot of pitting due to their leaky primers. Not an issue other than cosmetic.

I dont like the look.

Ive changed to CCI and Fed primers.

 

[XLR308]

From the picture it looks more like the bushing has been staked than gas cutting.

 

[Vicdiesel]

As stated earlier, I’ve done this myself, not to this extent.
I have a batch of Sellier and Bellot primers that are extremely soft. Sufficed to say, I don’t use them any more.

 

[Threadcutter308]

I will only speak for myself and I will say those pictures give me the heebie jeebies. I've never had that happen and if I did see it starting, my response would be along the lines of "Holy Shit"......I dunno, to let it get that bad seems akin to knowingly shooting reloads that have split necks.

I'd get a new bolt head pronto and find out why it was happening and take every step necessary to stop it from continuing.

 

[Supersubes]

From the picture it looks more like the bushing has been staked than gas cutting.

Looks like pitting to me, but if someone is staking their bushings in place like that, we need to out them, and do our best to make sure nobody uses them ever again.

 

[XLR308]

Looks like pitting to me, but if someone is staking their bushings in place like that, we need to out them, and do our best to make sure nobody uses them ever again.

Your probably right, my vision isn't quite as accute as it used to be.
Since I'm not an AI aficionado like many on here I have to ask since its also in the picture and caught my attention.
Why are there punch marks on the face of the bolt ?

 

[Supersubes]

Your probably right, my vision isn't quite as accute as it used to be.
Since I'm not an AI aficionado like many on here I have to ask since its also in the picture and caught my attention.
Why are there punch marks on the face of the bolt ?

Test to check hardness.

 

[Threadcutter308]

Your probably right, my vision isn't quite as accute as it used to be.
Since I'm not an AI aficionado like many on here I have to ask since its also in the picture and caught my attention.
Why are there punch marks on the face of the bolt ?

Saw those too............could be someone (maybe even the factory (?)) checking the hardness of the bolt. If it was the factory (?), probably nothing to worry about. If it was someone else (maybe checking hardness because of the pitting/cutting), that would be an additional concern.

Again, if it were me, I'd get a new bolt head pronto.

 

[FUNCTIONAL]

Saw those too............could be someone (maybe even the factory (?)) checking the hardness of the bolt. If it was the factory (?), probably nothing to worry about. If it was someone else (maybe checking hardness because of the putting/cutting), that would be an additional concern.

Again, if it were me, I'd get a new bolt head pronto.

Yup, like SuperSubes said its done at the factory to test the heads. I've only handled recent AIs but they have all had that on the bold face. Around the firing pin hole is another story...

 

[XLR308]

Test to check hardness.

That kind of threw me off since most of the pin tests I've seen done were on much larger components and leave a round indentation.

 

[Vicdiesel]

Got a hold of milehigh who said I would have to contact AINA directly for a bolt head replacement. Waiting on a reply from them. I’ll update when I get a response.

 

[LRI]

Just about every bolt I own sadly has some of that gas plasma cutting evident.

Winchester primers a few years ago matched with FGMM brass has been my cause.

Safe or not I cant say.

I shoot all my rifles though.

Your AR bolt is way beyond anything my rifles evidence of the problem.

If your AI has one or two pits I cant see it being an issue.

Well said.

 

[smoothy8500]

Dont load so hot and dont load loose pockets and you wont have the issue guys.

If the primer just falls into the pocket, drop both into a trash can and move on. Then evaluate how you’re killing primer pockets and work to avoid it.

Unfortunately, Winchester had a bad run of primers around 2009-2010 or so that "leaked" gas regardless if the load was proper pressure. Of course, it isn't noticed until after you've fired a few rounds and pitted your bolt. Considering how people were "hoarding" primers back then, cases of leaky primers are still floating around getting bought and sold.

 

[pmclaine]

Unfortunately, Winchester had a bad run of primers around 2009-2010 or so that "leaked" gas regardless if the load was proper pressure. Of course, it isn't noticed until after you've fired a few rounds and pitted your bolt. Considering how people were "hoarding" primers back then, cases of leaky primers are still floating around getting bought and sold.

That was when I bought my primers and it was right in the midst of the reloading supply drought.

3rd Gen Shooting Supply came through with Win primers and they were able to get some powder so I bought in bulk.

5000 each of large and small both have been exhibiting issues.

I sent some brass/primers back to Win and of course they said "No problem....top quality"

 

[carlsbad]

It isn't a safety issue but could lead to function issues. i call small dings in the face of the bolt cosmetic. But hot loads can result in hard bolt lift if the brass presses slightly into the depressions. Clearly there is a limit of how much bolt face you can be missing but I don't think you are approaching it.

If that bolt is bushed, and it looks like it may be, your problem may be a poor bush job. The Ai bolt is very hard (I think it is 17-4PH) and the face of the bolt is case hardened to the point that it is slightly brittle. It is very hard to puncture it with gas.

Because the boltface is so hard, it is very easy to chip if you don't use the right tooling. I can't imaging bushing a bolt like that without using an oversize bushing to cover the damage. That is what I would do if I received this bolt for a bushing job. What you may be seeing is chips that have fallen out that occurred during the bushing job.

--Jerry

 

[Vicdiesel]

Well, no dice on the new bolt as per AINA:

Hello Victor,

Reply from Service Manager:
A new bolt head cannot be purchased. The makes on the face of the bolt is gas cutting from primer pocket leaking gas. This is from reloading and the primers not being seated properly. A new bolt would have to be purchased. 20012BL is the AXMC 308 bolt, or he could go with a Small Dia AXMC pin and bolt assembly for the 308 AXMC bolt only(28340BL).

I guess I'll just mag particle the bolt face to make sure there aren't any cracks and keep an eye on it for now.

Thanks all for the responses.

 

[Milo 2.5]

Well, no dice on the new bolt as per AINA:

Hello Victor,

Reply from Service Manager:
A new bolt head cannot be purchased. The makes on the face of the bolt is gas cutting from primer pocket leaking gas. This is from reloading and the primers not being seated properly. A new bolt would have to be purchased. 20012BL is the AXMC 308 bolt, or he could go with a Small Dia AXMC pin and bolt assembly for the 308 AXMC bolt only(28340BL).

I guess I'll just mag particle the bolt face to make sure there aren't any cracks and keep an eye on it for now.

Thanks all for the responses.

There is a lot more reasons than properly seating a primer that causes gassing. Over pressure, headspace, primer fit from expansion of case head< sometimes a primer change can solve this.
Your first inspection of a case should be when putting fired rds back into ammo boxes, case mouth down, do a quick glance.
I'd clean my bolt face with a solvent and monitor going forward.