I don't know but I have had a ball shooting cast in my NM M1a BECAUSE it is a $1500 gun. Way less pounding on the op rod, the bedding job takes much less abuse, brass lasts longer, less recoil, barrel wear minimized, and costs a fraction of shooting match jacketed. Oh ya, zero fouling in the gas system and no leading. Bruce did his homework and I'm glad he has shared his carefully gathered results with us. You of course should do as you see fit with your gun. I just cast up another 1200 311299's many of which I will be running through my M1a this season.