Standard Products trigger marking

I'm completing a data sheet on a newly acquired Standard Products serial number 2230832 (2-44 Underwood barrel), so very late in production. Everything looks correct so far, but the marking on the trigger has me confused. At first I thought it was I-P, but after more research, I think it might be a poorly struck intertwined H-R, which could be either an IBM transferred part or an H-R part not marked S. Thoughts?

Edited by bigwagon - Feb 03 2026 at 8:45am

I agree with the OP's conclusion. There is not enough room for the "S" to the left of the "HR", so it must be either "HR B" (poorly struck) or just "HR". By the way, my STD PRO (SN 2113165) carbine has a lightly struck "S HR" trigger like that shown in Dan's attached post.