I THINK YOU SHOULD BE USING 2F IN THAT CAL. BUT 3F CAN BE USED WITH A REDUCE LOAD AT ABOUT 10%.A MAX CHARGE AROUND 100 GRAIN WOULD BE O.K. MYSELF I REALLY DON'T CARE FOR THE POWERBELTS HAVE TRIED THEM IN MY 50 C.V.A. @ 54 CAL T/C ALLWAYS WILL PICK UP A FLYER IN A 3 @ 4 SHOT GROUPE.COULD BE MY M/L LOADER IF FUNNY WHEN IT COMES TO POWERBELT. THE BULLET THAT WORKS FOR ME ARE PERCISION SABOT 40 CAL QT IN 235 GRAIN @ 330 FLAT NOSE MADE BY HARVESTER SABOT IN MY 54 CAL. HEY TRY POWERBELT YOU HAVE NOTHING TO LOOS IT MAY SHOOT GREAT FOR YOU.CHECK OUT THE PERCISION WEB PAGEhttp://www.prbullet.com/