Aye-Are-10.

first off, the lore is getting tweaked a little since it's successor, the M16 (or N16) existed before the Ay-Are-15's existence which led to the birth of the, yknow. N16.

The Ay-Are-10 is the battle rifle version of the Aye-Are-15 platform rifles, chambered in 7.62×51mm NATE, and is Designed by Eugore Steiner. When first introduced in 1956, the Aye-Are-10 used an innovative combination of a straight-line barrel/stock design with phenolic composite, a new patent-filed gas-operated bolt and carrier system and forged alloy parts resulting in a small arm significantly easier to control in automatic fire and over 1 lb (0.45 kg) lighter than other service rifles of the day.

FIRST CONCEPT OF THE AR-10 IN KE-RP, LORE MAY HAVE MISTAKES. REWORK IS ALLOWED