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AERO BCG’s

Okay, so how many have heard of 9310 bolts failing? Lots of manufacturers have shifted to 9310. For over a decade, the C-158 vs 9310 debate has continued. The carrier is standard 8620 steel while the bolt is 9310, as described on Aero's website. I have several of these exact BCGs and now have a few more coming my way.

Faxon Firearms seems to like the 9310 steel and I really like Faxon's barrels, so that is good enough for me...

https://faxonfirearms.com/blog/why-9310-steel-in-an-ar15-m16-bolt/
@cmshoot thoughts?
 
Okay, so how many have heard of 9310 bolts failing? Lots of manufacturers have shifted to 9310. For over a decade, the C-158 vs 9310 debate has continued. The carrier is standard 8620 steel while the bolt is 9310, as described on Aero's website. I have several of these exact BCGs and now have a few more coming my way.

Faxon Firearms seems to like the 9310 steel and I really like Faxon's barrels, so that is good enough for me...

https://faxonfirearms.com/blog/why-9310-steel-in-an-ar15-m16-bolt/

Fatigue...both are excellent but iirc the 158c is case hardened on the outside while still being somewhat malleable inside. It takes shock better essentially. The 9310 is harder yes, but the elemental composition makes it more prone to fracture under fatigue. That is also why you don’t see 9310 bolts proof tested often I believe.
 
Pull up the Aero part number in the description and get back to me. I was trying to inform, not debate.
Aero website does not pull it up either by SKU or UPC. It is a 9130 bolt, unless proven otherwise.
Normally 158 bolt is called out. If it is not, I suspect lesser steel.
Screenshot_20210325-181143.png
Screenshot_20210325-181100.png
 
I have a number of these, some with the logo and some without. Same as the Ballistic Advantage black nitride versions, just a different logo...

https://www.aeroprecisionusa.com/ar15-556-bolt-carrier-group-complete-black-nitride

Features:
M16-cut carrier
Machined from 8620 Tool Steel (Carrier) and 9310 Steel (Bolt)
Carrier has forward assist serrations
Black Nitride Finish - advanced lower friction coating that minimizes the need for lubricants and cleaning
Properly staked gas key
Shot peened
HPT tested/MPI marked
Black o-ring insert on extractor
High quality BCG

Specs
Made In America? Yes
Select Your Finish Black Nitride
Platform AR15
Bolt Material 9310 Steel
Carrier Material 8620 Steel
Weight(s) 11.52 oz
 
Aero website does not pull it up either by SKU or UPC. It is a 9130 bolt, unless proven otherwise.
Normally 158 bolt is called out. If it is not, I suspect lesser steel.
View attachment 3186198 View attachment 3186199

It's new old stock according to my buddy, who is a distributor. Two seconds on google and you can see OpticsPlanet still has it in the system with the entire description instead of the generic on most other sites.

Features of Aero Precision APRH100615 AR15 Bolt Carrier Group:
  • M16-cut carrier
  • Machined from 8620 steel
  • Carrier has forward assist serrations
  • Black Nitride Finish - advanced lower friction coating that minimizes the need for lubricants and cleaning
  • Properly staked gas key
  • 5.56 Bolt is machined from Carpenter 158 tool steel
  • Shot peened
  • HPT tested/MPI marked
  • Black o-ring insert on extractor
  • High quality BCG
Edited to add, several other sites also show it as carpenter. It could possibly be 9310 as they switched over but I could only find one instance where that sku is associated with a 9310 bolt. In either case, it's a quality bolt.
 
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