BCG Mistake


MIO Type 10 Manufacturer
I just got my newest shipment of BCG's in from my supplier. They are a major supplier and produce tens of thousands of them per month, I've always been happy with what I receive.
However, this time when I opened the box I was surprised to find the bolts were 9310 instead of Carpenter 158. They have been shot peened, MP inspected, etc etc, but the rifles we build call for 158.

So I'm left with a couple options, I can return them, or I can offer them one time only at drastically reduced dealer pricing to you guys. Due to dealer agreements, I won't be able to offer this again.

25 Mag-phosphate and 21 Nickle Boron.

$200 for Mag-phosphate ($130 Boomer Shooter Price)
$275 for Nickle Boron ($155 Boomer Shooter Price)

Let me know if anyone is interested.

- Matt


Scott Hearn

Well-Known Member
mike cyrwus said:
the dif is being able to call a part milspec or not.. if I remember correctly
That's pretty much it, Mike. The chemical properties are almost identical. If these were heat treated the same, one could consider them the same. (Disclaimer: I've machined literally tons of AISI 9310)


MIO Type 10 Manufacturer
From my understanding there's not a huge difference. 9310 can be slightly tougher, but the heat treat process is much more finicky then 158.
It really comes down to personal preference and yes the ability to call something mil-spec.
Yes, these are full auto carriers and if any of you have proper paperwork, I've got the rest of the full auto goodies as well.

- Matt

Latest posts