What do the Hunter Arms proof marks mean?

Hunter Arms proof tested their barrels in house and the statement “All L.C. Smith guns are guaranteed to shoot any Nitro Powder made” appeared in advertisements as early as 1894. The L.C. Smith listing in the 1908 Sears, Roebuck & Co. Catalogue No. 117 included “Bored For Nitro Powder” (both Armor and Damascus barrels) and the Notice “All our guns are tested with heavy loads and cannot burst except by carelessness, obstruction in the barrel or improper home loaded shells with nitro or dense powder.” The stylized PM and HACo in a square over NP did not appear on the barrel flats however until about 1922.

       Barrel flats of a 3" chamber Specialty Grade  

       Close up of Proofmark

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. This figure would have been obtained using lead crushers (LUP) and corresponds to a modern transducer measurement of 15,500-16,000 psi.

PLEASE NOTE - The Proof Pressure is approximately ONE AND ONE-HALF times the intended Service ( or Using ) Pressure. The modern SAAMI maximum service pressure for 2 3/4” 12g shells is 11,500 psi. 

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.  

For more information regarding appropriate loads for your L.C. Smith. 

(click on image for a larger view)