I just received the AIM surplus bolt carrier, which many of you may know about due to its amazingly low price of $79 dollars shipped.
Here is the feature list:
- Features 9310 Bolt Material
- 8620 Chrome lined carrier and gas key
- Properly staked Investment cast gas key hardened to USGI specifications fastened with Hardened Grade 8 Fasteners
- Shot peened MPI (Magnetic Particle Inspected) Bolt
- Extractor O-Ring upgrade with Black Insert
What interested me was the bolt material. Typically the AR15 community looks for C-158 which is a blend of steel from Carpenter. 9310 is also a Carpenter product, but the make up of the steel differs between the two. What I surmised was that 9310 should be a better bolt material as long as it is properly heat-treated. It is less brittle than C-158 and theoretically stronger as long as it is made properly. I have seen several arguments over the two materials in my research, but overall “flip a coin” when choosing which material.
The bolt carrier and bolt group is one of the best I have ever seen. The machining is superb. Edges have been smoothed, no machine markings are present, and the overall look of the bolt is a professional job.
The staking needs to be a bit deeper to make sure the key does not come loose, but I can do that here at home.
If the product performs well in my budget rifle build, I will be happy. I don’t see any reason to believe it will perform poorly.