[Squantos]

Go with the 3.8 pound OIP variant in .243 Winchester with th HK piston design.

http://www.gunsamerica.com/blog/oip-3-8-pound-ar-shot-show-2015/

[Redcitizen]

Very nice! I could go for a AR rifle in that caliber.

Found an article touting the usefulness of the .243 as a service round.

http://www.chuckhawks.com/243_service_rifle.htm

[papertyger]

Ooooooo....Now that DOES make my little heart patter ;)

[familyop]

Please disregard my earlier ignorant comment about burning speed. A .243/6mm about 85-90 gr. could probably do really well with a military barrel at a reasonable speed.