If you beat on metal parts long enough they will eventually yield. I doubt that the bolt head and breach ring in that rifle have gained any headspeace but that is easy to check with gauges.
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AI AT308 bolt face pitting
- Thread starter Mareshow
- Start date
Probably not any additional head space, but I was kind of wondering how that many too high a pressure rounds would effect the chamber. Probably not in the realm to effect the chamber but while I had a manufacturer of what is widely considered to be the best precision rifle made, I thought I'd dig for more information.
If you cant say something factual and informed, it's probably best to say nothing.
What you can't see is the proof engraving on the side of the bolt head after proof testing with two high pressure proof loads.
Here's an image of one of my recent souvenirs. A massive over pressure event with an AX338 Lapua Magnum due to an "owner provided" bore obstruction. The bolt opened without undue resistance, the action easily passed headspace. If the split did not run back to the chamber you could have cut the damage off and shot it again safely. The images I posted are from legitimate over pressure events. Parts have yielded, but otherwise performed as designed (i.e. did not completely let go). Gas leakage due to expanded primer pockets doesn't come close to these pressure levels. Just run 70,000 or so PSI loads with brass not made by Lapua, ADG, Peterson, and a couple of others and you will get there pretty fast. How many times have you read on the interwebs some guy getting 2900 fps with a 6.5 Creedmoor and 140 grain bullet? It isn't possible at safe, reasonable pressure levels, and yet guns tolerate it until the GD fool decides to add another .5 grains of powder . . . Wasn't seeing any pressure signs!
Not all over pressure events turn out this way. The second image is an AI bolt head and what is left of the case head. The extractor is FUBAR as is the bolt and lock ring. This is from a "high pressure" hand load. The primer is not pierced. Brass, in a plasma state, has been "plated" to the parts. The barrel and chamber were completely OK and reusable. The brass is the weakest link in the chain. The gas leakage shown in the OP clearly does not rise to a level that will cause the metal to yield. The damage done to the bolt face is not pressure induced and it does not affect the chamber. The metal removed by gas cutting from leaking primer pockets is like cutting metal with an acetylene torch. It is the result of extremely high temperature gas, not massive over pressure as demonstrated in the images below.
As I said earlier, this is like getting a hard knuckle rap to the forehead before cashing in your life insurance policy. If this doesn't make sense to you and you want to say the manufacturer of the firearm was somehow at fault, you should consider taking up golf or badminton. People f__k up guns all the time and lie about it. The rate of truth to lies is about 33% to 66%. The OP was lied to and now there is a long thread dragging a stinking, rotting lie to AI's doorstep.
Don't be that guy.
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Thank you for the expert opinion. Although unfortunate that the new owner has an ugly bolt, he did state getting a low price on the rifle. This information will allow him to consider if the price matches the overall value or argue for money back.
If you are referring to the barrel that is split nearly end to end, yes.
I said in a previous post that it was a bore obstruction. The owner left a laser bore sighter in the muzzle and fired a round.
That 338 barrel and handguard split is nasty. Those parts would be a great addition to the "wall of shame" for sure. I have a "wall of shame" for parts from engine failures, but so far luckily no such wall for catastrophically failed gun parts...
Was the rifle able to be returned to service? I'm assuming the breech ring, bolt, and barrel were replaced, even if the headspace checked out ok after that, but I'm curious if the front of the action or the threads in the action were flared out or otherwise damaged from the split barrel.
Also, am I seeing things right where the barrel split and broke just behind the muzzle threads and shoulder? I'm guessing the muzzle threads remained in the brake or suppressor?
Yikes!
Thanks for all the info you've posted in this thread, Scott.
Looks like that large pin (0.080") .308 bolt was used in a .260 rifle instead of the small pin (0.062"). Peak pressure duration - pierced primers.
ETA: I have seen someone attempt to run a small diameter pin in the large diameter bolt without being bushed (not AI).
ETA: I have seen someone attempt to run a small diameter pin in the large diameter bolt without being bushed (not AI).
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Hi,
Holy Crap, lololol
People are literally still typing it's from pierced primers although the damn manufacturer has provided sufficient evidence to prove otherwise, lolol
Just cannot make it up............
Sincerely,
Theis
Holy Crap, lololol
People are literally still typing it's from pierced primers although the damn manufacturer has provided sufficient evidence to prove otherwise, lolol
Just cannot make it up............
Sincerely,
Theis
so you're thinking loose primer?
ETA: Older thread
https://www.snipershide.com/shooting/threads/ai-ax260-pierced-primer.133740/
ETA: Older thread
https://www.snipershide.com/shooting/threads/ai-ax260-pierced-primer.133740/
He'll yeah I have changed/ improved
30,000 rounds and counting reloads
Over last 6 years. I have learned some hard lessons and I claim full responsibility for my fuck-ups
Hi,
How about read the thread and pay close attention to everything @Scott Seigmund says...Just FWIW...He IS Accuracy International North America, lol
Sincerely,
Theis
Theis, if you send me a demo rifle for a week I still have some of those defective pinholing WLR primers on hand-- I can load some up for gas erosion testing on one of your fancy aermet 100 bolts.
After 100 rounds or so with those defective primers I will post pictures of the torched boltface to your official Hoplite thread and we can bring this show over to your house.
Be sure the rifle you send me has a few extra hardness tester imprints on the bolt head for additional wild speculation, lol!
Sounds like a serious and interesting experiment. I would chip in on shipping so Theis isn't out of pocket on anything.Theis, if you send me a demo rifle for a week I still have some of those defective pinholing WLR primers on hand-- I can load some up for gas erosion testing on one of your fancy aermet 100 bolts.
After 100 rounds or so with those defective primers I will post pictures of the torched boltface to your official Hoplite thread and we can bring this show over to your house.
Be sure the rifle you send me has a few extra hardness tester imprints on the bolt head for additional wild speculation, lol!
Bolt head needs swapping out for a new one - easy replacement with the roll pins on AI
Or send for the bolt faces to be re machined but that will
Be hard on tooling
The damage has been caused by gas leak from primers with hot loads
Or send for the bolt faces to be re machined but that will
Be hard on tooling
The damage has been caused by gas leak from primers with hot loads
Not sure if you read anything Scott posted or just coming up with half ass info
I read what Scott posted and agree - it’s pitting causes by high pressure gas
The bolt head of the gun needs swapping for a new one
Ai bolts have interchangeable heads - they are held to the bolt body with roll pins
Look at any A I bolt and you will see it’s two parts
The bolt body and the lug / bolt head
No smart ass reply - it’s fact
The bolt head that’s has been torched can be replaced easily with a new part
The OP was sold something bad, I’ve offered the solution
The bolt head of the gun needs swapping for a new one
Ai bolts have interchangeable heads - they are held to the bolt body with roll pins
Look at any A I bolt and you will see it’s two parts
The bolt body and the lug / bolt head
No smart ass reply - it’s fact
The bolt head that’s has been torched can be replaced easily with a new part
The OP was sold something bad, I’ve offered the solution
We don't sell just the bolt head, but we do sell the bolt "assembly".
Based on the depth of the pitting on that bolt face, I wouldn't be pissing around with machining the bolt face. I would just get a new bolt assembly, or let me rephrase that, have the guy who fucked me over pay for it.
If the seller didn’t inform the buyer of the bolt issue before purchase I feel the seller should be replacing the bolt assembly, otherwise shit head status is confirmed.
But he's part of a big shop in
I’m torn...
On one hand, I agree with Scott’s sentiment that a thread title containing ‘AI’ and ‘bolt face pitting’ is akin to linking the two...which invites baseless speculation. (it’s OBVIOUSLY user error)
On the other hand, it got me to read the thread... which has not only added to my knowledge (keep an eye on my bolt faces, shoot normal loads, continue to toss sloppy pocketed brass, don’t buy Win primers, or use laser bore sighters)...
But even more importantly, this thread added to my day’s morale as the Hide continues to provide merciless feedback to those that don’t read good.
On one hand, I agree with Scott’s sentiment that a thread title containing ‘AI’ and ‘bolt face pitting’ is akin to linking the two...which invites baseless speculation. (it’s OBVIOUSLY user error)
On the other hand, it got me to read the thread... which has not only added to my knowledge (keep an eye on my bolt faces, shoot normal loads, continue to toss sloppy pocketed brass, don’t buy Win primers, or use laser bore sighters)...
But even more importantly, this thread added to my day’s morale as the Hide continues to provide merciless feedback to those that don’t read good.
Clearly you’ve never fit/chambered a barrel to an AI receiver. You’re wrong.
Hi,
Geezus Christ!!!!!!!!!!!
Where do some of you get your information from????????
Lets get a bolt head (Even though AI does not sell bolt heads)
Lets machine out pits that are so deep that the damn extractor would damn near be onto the cartridge case body.
Lets then machine the tenon so that absolutely zero AI barrels headspace properly.
Lets just get a new Flipping bolt and call it a day, lololol
Sincerely,
Theis
Geezus Christ!!!!!!!!!!!
Where do some of you get your information from????????
Lets get a bolt head (Even though AI does not sell bolt heads)
Lets machine out pits that are so deep that the damn extractor would damn near be onto the cartridge case body.
Lets then machine the tenon so that absolutely zero AI barrels headspace properly.
Lets just get a new Flipping bolt and call it a day, lololol
Sincerely,
Theis
The OP has two options
Buy a new bolt or bolt head (I’ve no idea what’s available as spare parts in the USA )
But sat in MY workshop, I have some spare AW bolt heads
Machining out the pitting is another option using carbide tooling
The pitting is likely to be no more than a few thousandths deep and relatively easily removed with appropriate tooling
Though it looks bad it may be possible and it’s inpossible to measure the depth of the pits from an inline image
Obviously removing material from the bolt face would cause headspace issues - therefore removing what’s taken from the bolt face (for example .003”) would need the same removing from the shoulder moving the barrel back up its original position in terms of headspace datum
It was so obvious I didn’t mention it but as it’s been brought up negatively,,,
Oh and yes, I’ve re barrelled numerous AW, AX and AT rifles over a period of several years - all passing proof testing in my country and all shooting very well
Altering the tenon and bolt face would not cause any other issues than a blueprinting job on any action
The only issue I foresee would be if the op were to use pre fit barrels
In that instance a new bolt would be best - keeping everything to factory spec
Buy a new bolt or bolt head (I’ve no idea what’s available as spare parts in the USA )
But sat in MY workshop, I have some spare AW bolt heads
Machining out the pitting is another option using carbide tooling
The pitting is likely to be no more than a few thousandths deep and relatively easily removed with appropriate tooling
Though it looks bad it may be possible and it’s inpossible to measure the depth of the pits from an inline image
Obviously removing material from the bolt face would cause headspace issues - therefore removing what’s taken from the bolt face (for example .003”) would need the same removing from the shoulder moving the barrel back up its original position in terms of headspace datum
It was so obvious I didn’t mention it but as it’s been brought up negatively,,,
Oh and yes, I’ve re barrelled numerous AW, AX and AT rifles over a period of several years - all passing proof testing in my country and all shooting very well
Altering the tenon and bolt face would not cause any other issues than a blueprinting job on any action
The only issue I foresee would be if the op were to use pre fit barrels
In that instance a new bolt would be best - keeping everything to factory spec
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Can’t believe this thread is still going, as Theis said get a new bolt. Not sure why you would machine the bolt or tenon. Then no prefits, why bother.
It was stated that the previous owner said the heat treating of the bolt head was defective. Once the "pile" is dropped on the ground the bugs come out to feed.I’m torn...
On one hand, I agree with Scott’s sentiment that a thread title containing ‘AI’ and ‘bolt face pitting’ is akin to linking the two...which invites baseless speculation. (it’s OBVIOUSLY user error)
On the other hand, it got me to read the thread... which has not only added to my knowledge (keep an eye on my bolt faces, shoot normal loads, continue to toss sloppy pocketed brass, don’t buy Win primers, or use laser bore sighters)...
But even more importantly, this thread added to my day’s morale as the Hide continues to provide merciless feedback to those that don’t read good.
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So you machine the bolt counterbore enough to eliminate the pitting. And then what?
0. What do you do with the extractor that is now too long?
1. The ejector plunger is now proud of the bolt face. How will you deal with it. Will it still function properly after you continue to alter it?
2. Your firing pin is too long. How do you intend to correct that?
3. As stated earlier, the headspace of the chamber has to be corrected.
So, you pay a gunsmith to do this work and what is the cost? It's going to be the same or more than replacing the bolt with an OEM part.
I can't believe it's still going on either, and my commenting is just prolonging the agony.
If I can help persuade an owner from going down a rabbit hole chasing bad advice and it keeps me from seeing another botched job like this, I guess it's worth it.
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Good on you Scott, plenty of bad advice in this thread. At least you here to keep the sanity. You can only advise people, and hope they listen.
You assess the pitting to see how deep it actually is before conducting any rectification work
If the pitting is so bad it may affect the relationship pf the extractor to the bolt nose then why on earth would you continue ?
The Ejector plunger is always proud of the bolt face Scott (unless the weapon is loaded with a cartridge in the chamber and bolt closed) - it wouldn’t work otherwise
Firing pin depth is easily altered on most of not all Accuracy International actions (you should know this I hope ?)
Chamber headspace - again easily altered by machining the tenon shoulder and rear face
But (and I stress this point) as it’s clear that everything needs to be spelled out in simple terms
If the pitting is so bad - that the rectification work would unduly affect the extractor then you wouldn’t even start the work
Purchasing a new bolt is the answer
(A new bolt head would be the most cost effective part to replace if it were available in your country )
