powder all the way. Look at the new custom shop 5-35c cart, made up with Savage. They use a superfat cart, with concave shoulders, and a long neck, also uses proprietary powder mix. this round uses about 20 % less powder than a 223, and yet moves a 35 grain bullet about 4800 fps. with it's super long neck, the powder plug, as it moves, is rebounded into by pressure, then moves up the blast column of the case, gets hotter, and hotter. As it begins to get into the shoulder/neck area, it us superhot, but the plug is almost completely burned up. By the time it gets into the neck of the cart., it is now burning out, and the brass of the neck swallows up the excess heat rapidly, then displaces it. this cart., shows excellent throat wear/ bbl life.