Dynomike, for avoir, or more correctly, avoirdupois weight, which is used for weighing powder, just remember that there are 7,000 grains per pound, so divide by 16 oz. and you get 437.5 grains in each ounce (oz.). That's it.
Sometimes the Troy Weight system used to weigh precious metals and gems is confused with the Avoirdupois system weights. This is incorrect. They are COMPLETELY separate and different.
Troy Weight
Unit Grains Grams
Troy pound (12 troy ounces) 5,760 373.241 721 6
Troy ounce (20 pennyweights) 480 31.103 476 8
Also, we would like to relate to armorer 77 our method for conducting similar tests. We dig a 24" deep hole in the ground to contain all debris, should the tube being tested fail and put a looooong fuse on it and retire to a special 7,600 pound steel barricade built for us by General Motors Corp., the OLD GMC, a Suburban which is parked 50 yards away and BELOW the crown of the testing hill. We never had a tube fail yet, but testing to destruction was never on the menu. A standard three times service load of powder and two times shot weight is always used during these prototype tests. This was one of the testing methodologies used during the War for Southern Independence. Stay safe, Armorer 77, stay safe.
Regards,
Mike and Tracy