In 1965, the U.S. Marine Corps began its search for a new rifle and scope combo to serve as their official combat sniper rifle. The goal was to have USMC armorers customize and accurize a readily available production rifle. The Corps settled on the Remington Model 40x, chambered for the .308 Winchester (a.k.a. 7.62 NATO) cartridge, and topped it with a commercially available 3-9x40mm hunting scope with an Accu-Ranging scale. The rifle was designated the M40.
