I remember something somewhere though that the arrow weight was heavier in per gram X bow poundage.
Most people don't shoot anywhere near the poundage with their traditional bows that they do with compounds. A 400 gn arrow on a 70 lb compound is 5.7 grains per pound. The same 400 gn arrow on a 50 pound recurve is 8 grains per pound. Same arrow weight, but it's heavier in relation to the draw weight.