Gunaddict1962, brand new cases have always shot most accurate in all the USA service rifles. Some of the military teams tried full length sizing their fired match cases only to have them shoot worse than new ones; same with commercial match ammo.
The reason's the bolt face in those rifles were never squared up. Any new round fired in them ends up with its case head way out of square. It's never squared up in any reloading process so they shot poorly.
The above aside, proper full length sized cases in high power rifles has always give best overall accuracy for decades. Even the benchresters moved away from neck only sizing not too long ago and now use full lengths sizing dies with bushings sized for their cases.
Dan, most folks shooting semi-autos give their cases a full length sizing, not only to make chambering easier, but because they're more accurate. Even on those whose bolt face is only minimally out of square. Nobody's ever reloaded loaded fired cases from semiauto USA 30 caliber service rifles that shot as accurate as Federal Gold Medal Match or the late 1960's National Match lots of M118 ammo with brand new cases in those huge MIL SPEC chambers. Go figure. . . . .
US Navy Distinguished Marksman Badge 153
Former US Navy & Palma Rifle Team Member
NRA High Power Master & Long Range High Master
NRA Smallbore Prone Master