Heat treatment on ar trigger group pins?

[diegocn]

I need to make a set of custom length anti-walk AR trigger group pins. They will be made from annealed 4140 so I imaging they need to be heat treated.

What is there hardness I should be aiming when heat treating the pins?

 

[Jonnyofalltrades]

Annealed 4140 has over 90kpsi tensile strength as is. Certainly adequate.
Are you drilling and tapping the ends? Or just grooving? If it's only grooving, I would start with hardened pin stock, if you really must have hardened pins. It would be straight and smooth, which is more than can be said of most small parts after quenching.

 

[Blastattack]

The spec on the pins is 72.5-76 on the 15N scale. That equals 24-32 Rockwell C. Material is 4130 or 4140.

 

[Jonnyofalltrades]

The spec on the pins is 72.5-76 on the 15N scale. That equals 24-32 Rockwell C. Material is 4130 or 4140.

Interesting. I often work with 4140HTSR(heat treated, stress relieved). It usually comes from the supplier around 42 Rockwell C.
Not easy to machine, but beautiful stuff.
I don't work on AR's at all, but aren't the trigger group pins all 5/32" diameter?

 

[Blastattack]

Interesting. I often work with 4140HTSR(heat treated, stress relieved). It usually comes from the supplier around 42 Rockwell C.
Not easy to machine, but beautiful stuff.
I don't work on AR's at all, but aren't the trigger group pins all 5/32" diameter?

The pins are 0.154" +.0000 -.0005

 

[DANS40X]

OP,
Your concern should be the receiver hole diameter(s) of an AR aluminum anodized lower.

Gage pin the receiver hammer & trigger pin holes....first.

Anti ROTATION pins will not allow pin rotation that will wear the anodizing of the receiver pin holes.

Ground finish Oil hardened drill rod or 360 brass would suffice for AR hammer/trigger pins.

 

[diegocn]

The spec on the pins is 72.5-76 on the 15N scale. That equals 24-32 Rockwell C. Material is 4130 or 4140.

Thank you!

I'll be drilling and tapping both ends for 4-40 screws hence I had to start off with annealed 4140.