Which do you prefer and why? Have you ever seen an instance where one performed better/worse than the other?
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Carpenter 158 vs 8620 vs 9310
- Thread starter Hasselhoss
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It's my understanding that the 158 is mil spec for the bolt, 8620 is spec for the carrier and 9310 is less than 10% harder than the 158.
I think I've read somewhere that 158 was a proprietary from one company and that it is case hardened. I'm not a Metallurgist and half way illiterate but there might be a reason why you would case harden something leaving it softer in the center. It would be interesting if someone had a long term wear study on this.
I think I've read somewhere that 158 was a proprietary from one company and that it is case hardened. I'm not a Metallurgist and half way illiterate but there might be a reason why you would case harden something leaving it softer in the center. It would be interesting if someone had a long term wear study on this.
Anyone who competes with their ARs will tell you to stay away 8620 for the bolt, simply cause it wears faster and is prone to busting. I prefer 9310 or C158, either is fine.
You're carrier is almost always 8620, which is mil-spec. So no worries there.
Carpenter 158 is a case(surface) hardened steel where 8620/9310 is through hardened. Case hardening allows C-158 to be very hard on the outside to prevent wear and crack formation while the inside is softer and more flexible to prevent crack propagation and absorb shock loads.
8620/9310 being through hardened can either be softer and better at shock, or harder and better at wear but not both. 9310 is about 8% stronger in either category than 8620.
It should also be noted that 8620/9310 can be case hardened via carburizing.
I use standard 8620 carriers and only 9310 or Carpenter 158 bolts. Bolts break all the time, especially the lugs, but it's much more often when an 8620 bolt is used.
You're carrier is almost always 8620, which is mil-spec. So no worries there.
Carpenter 158 is a case(surface) hardened steel where 8620/9310 is through hardened. Case hardening allows C-158 to be very hard on the outside to prevent wear and crack formation while the inside is softer and more flexible to prevent crack propagation and absorb shock loads.
8620/9310 being through hardened can either be softer and better at shock, or harder and better at wear but not both. 9310 is about 8% stronger in either category than 8620.
It should also be noted that 8620/9310 can be case hardened via carburizing.
I use standard 8620 carriers and only 9310 or Carpenter 158 bolts. Bolts break all the time, especially the lugs, but it's much more often when an 8620 bolt is used.
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Double post...
Thanks for the info. I am building another AR and the BCG that came with the upper is described as Carpenter 158 with no further details.
i wouldn't have any hesitations in using it.
This was said backwards 9310 is 7% stronger then 158carp steel.. At least that's what the books say
6 year old thread.Carry on
some of us aren't as old as you and need new info
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