Seems he's looking for both, I'm suggesting nitride for both over phosphate. I like the stuff. Assuming nitrided bore, it's a big step up over phosphate. Good to know PSA never sells non-C158 bolts. They definitely do sell BCGs they don't specify as Toolcraft. In the top kit of the op, the bolt is specified as both C158 and then below as 9130....
PSA can be misleading, but all are Mil Spec so when asked they said the 9130 was the bolt carrier, and the bolt is Carpenter 158 which matches the actual mil-spec. Have built 4 from them and the only problem I encountered was a SS A2 MOE freedom mid length 16” upper that was a little loose on the upper to lower fit on 4 lowers, an accu wedge took care of that issue and the rifle was a solid minute of coyote @300.
I got away from the MOE and went with lightweight M-Lok as I found the MOE to cumbersome in some respects and definitely added too much weight for an all arounder.
8620 (normalized). This is the MIL-SPEC (MIL-S-16794)
alloy used to machine the bolt carrier.Tensile Strength: 640 MPa
Yield Strength: 360 MPa
9310 (normalized).
Tensile Strength: 910 MPa
Yield Strength: 570 MPa
Carpenter 158. This is the MIL-SPEC
alloy used for the bolt.
Tensile Strength: 1103 MPa
Yield Strength: 931 MPa
S7 Tool Steel.
Tensile Strength: 2030 MPa
Yield Strength: 1520 MPa
