The bolt of the AR-10\308 rifle is broken.

Venäjä77

Private
Minuteman
Mar 13, 2025
11
5
Finland
I won't say who made the rifle, but the price of the rifle is more than 2000 euros and the quality of the rifles is well known. I bought a brand new rifle and fired about 1,200 rounds from it, always fired with a silencer, an adjustable gas unit, no overgas. The cartridges are commercial, there were no signs of overpressure. I shoot a lot with different AR-15 223 rem and after several thousand shots I have never encountered problems with the bolt of rifles. There is a breakdown on the new AR-10 308, which is not the cheapest, after 1200 shots. The question is: do ar-10 rifles often have bolt failures? Or in my case, just a defective part?
 

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1,200 rounds shouldn't break that bolt head, but... I've seen them break with less. I've seen ar15 bolts get 30k rounds, but I saw one break at less than 500rds once. I think it might be a place where spending a couple extra dollars is worth the investment. I've been shooting 6arc since it was announced, and I've read about severall people complaining about broken bolt heads. If you buy JP bolts and bolt heads, they just don't seem to have that kind of trouble. An ar10 is a far more violent cycle, and it's brutal on the bolt head.
 
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That isn’t an AR-10 bolt for starters.

iu


It’s an AR-15 bolt with a .473” cartridge bolt face, with dual ejectors.

This means it can only be a Ruger SFAR bolt.

POF Rogue has a single ejector, so it isn’t that.


AR-15.......................SFAR...................ArmaLite AR-10
iu

Yep I have one in the shop, look like the Ruger 308 bolt
 
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One thing I noticed was that POF did a lot of their high-volume testing using Russian steel case .308 Winchester ammunition.

Russian steel-cased .308 was loaded to much lower working pressures, some sites claiming 42,700psi even.

So when POF was validating their pressure containment and durability of the small frame AR-15 chambered in .308, most of the ammunition was not anywhere near SAAMI MAP.

Ruger of course knocked-off the POF Rogue when they made the SFAR, using similar pressure containment approaches with AerMet super alloys for the bolt and barrel extension, while also adding vent holes in the extension and upper receiver in case of a case failure catastrophic malfunction.

So it doesn’t surprise me to see a part failure, especially for a rifle priced in the $1k region.

I would also look at the receiver face and see if it is square. Being out of square causes asymmetric loading on the bolt lugs, and the lugs adjacent to the extractor pocket are the weakest.

You can use the Wheeler receiver face lapping tool to check if your receiver face is square.
 
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One thing I noticed was that POF did a lot of their high-volume testing using Russian steel case .308 Winchester ammunition.

Russian steel-cased .308 was loaded to much lower working pressures, some sites claiming 42,700psi even.

So when POF was validating their pressure containment and durability of the small frame AR-15 chambered in .308, most of the ammunition was not anywhere near SAAMI MAP.

Ruger of course knocked-off the POF Rogue when they made the SFAR, using similar pressure containment approaches with AerMet super alloys for the bolt and barrel extension, while also adding vent holes in the extension and upper receiver in case of a case failure catastrophic malfunction.

So it doesn’t surprise me to see a part failure, especially for a rifle priced in the $1k region.

I would also look at the receiver face and see if it is square. Being out of square causes asymmetric loading on the bolt lugs, and the lugs adjacent to the extractor pocket are the weakest.

You can use the Wheeler receiver face lapping tool to check if your receiver face is square.

That's not how engineering works in a relatively large liability conscious organization. Ruger's bolt isn't a direct copy of the POF, even if it was there's 0% chance that they just copied the POF bolt, picked a similar material and did no validation of the strength, fatigue life, or just ran a bunch of steel cased wolf or whatever. I run an engineering group, and this just isn't how things work, nothing gets released like that.

What's far more likely, if this is an SFAR bolt failure, is that there was some material defect, or defect in lock up geometry that caused a stress concentration that lead to premature lug failure.
 
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I shot 60 rounds, everything worked fine. I found the problem this morning when I was cleaning my rifle.

I guess if you dont have a basis of comparison its hard to know if it was 100% running correct. Could appear to run fine but could be cycling a bit violently. Overgassed or weak buffer. Was ejection pattern right on? Any extraction/ejection issues?
Did the extractor pin break and the extractor get slammed in there and that could have caused the bolt to break? Did you take the extractor off? If so was it sloppy? Forward and back play? Need better pics of bolt, extractor, inside the chamber, barrel extension. My guess is the bolt broken is secondary damage from something else that happened. Need to figure out exactly what happened.