I got this brake with a barrel I purchased. The original owner was unsure who made it, and I'm just trying to nail that down. What do you think? It is 338 cal.
The OD to the round portion is 1.188, to the flat is 1.02. The shank is od is .902 and as best as I could get the threads are .57 to the inside and .64 to the outside. There are no markings at all.