Posted by Drew Hause on January 7, 2014, 9:15 am, in reply to "damascus pressure"
Sorry, but must include this: Nothing posted implies that your gun is safe to shoot, with any load.
Answer: the barrels were intended for black or nitro powder
We don't know the original proof pressures, but LTC Calvin Goddard, writing in "Army Ordnance" in 1934, stated that Hunter Arms proof tested 12ga 2 3/4" chamber barrels at 14,300 psi.
PLEASE NOTE - The Proof Pressure is approximately ONE AND ONE-HALF times the intended Service (or Using) Pressure.
L.C. Smith hang tags after about 1920 indicated the standard 12 gauge load was for 3 Dram Eq. with 1 1/8 oz. shot. Modern Winchester 1 1/8 oz. 3 Dram Trap loads have been measured at 1,200 fps with a pressure of 9,600 psi.