Hello. I am new to reloading,and I am planing to reload 85 gr TSX Barnes bullets in .243 wit Hunter and Varget powders.I bougt the Barnes reloading manual number 4,and it mentions for this load : Federal primers GM210M,so I have being trying to get them with no succsses. In other chapter, for .308 it mentions Federal 210,for other caliber 210M; at Cabela web site they only mention federal 210 Large Rifle. Is the federal GM210M diferent from 210,210M.210 Large rifle ? Can any one be used for this load? Any idea why the manual uses diferent letters? Any information will be apreciated.