text: In 1938, the unstained, , flat-base bullet combined with the .30-06 case became the M2 ball cartridge. The M2 ball specifications required  minimum velocity, measured  from the muzzle. M2 ball was the standard-issue ammunition for military rifles and machine guns until it was replaced by the 7.62×51mm NATO round in 1954. For rifle use, M2 ball ammunition proved to be less accurate than the earlier M1 cartridge; even with match rifles, a target group of  diameter at  using the  M2 bullet was considered optimal, and many rifles did not perform nearly as well. The U.S. Marine Corps retained stocks of M1 ammunition for use by snipers and trained marksmen throughout the Solomon Islands campaign in the early years of the war.
  In an effort to increase accuracy, some snipers resorted to use of the heavier .30-06 M2 armor-piercing round, a practice that re-emerged during the Korean War. Others sought out lots of M2 ammunition produced by Denver Ordnance, which had proved to be more accurate than those produced by other wartime ammunition plants when used for sniping at long range. With regards to penetration, the M2 AP round can penetrate at least  of armor steel at . A test done by Brass Fetchers shows that M2 AP can actually penetrate up to  of MIL-A-12560 armor steel from a distance of . The round struck the plate at a velocity of 2,601 fps and made a complete penetration.