What are Impact 737's made of?

Halffull

Supporter
Supporter
Full Member
Minuteman
Mar 26, 2022
100
27
SE Oklahoma
I can't seem to find out what material Impact Precision uses for their actions and bolts. It seems they are closely related to Surgeon and I see they advertise 4140 for their actions. This is purely trivial on my part. Does anyone know?