[quote=@iHxzardx]
[@MatthiasAngel] Marines now-a-days are only using .223's as regular ammunition and with this being future a bullet advance could have been made and possibly the .22 is strong enough now! My character is probably going to use a .22 .223 or simply an air rifle most likely, along with a spear or sword of some type *shrug* all im saying is that a .22 or .223 is an excellent marksman rifle.
[/quote]
Yes, Most US Army and USMC units use the M4 Carbine which takes a 5.56mm (.223 Caliber) round. Infantry units also use an upgraded version of the older M14 for a Squad Designated Marksman which fires 7.62mm (.308 Caliber) if you are looking for a heavier slug. Also USMC Training bases (Camp LeJeune, NC and Camp Pendleton, CA) have a ready supply of rifles that fire 7.62mm Ammunition. US Marines spend a LOT OF TIME firing these rifles on Known Distance (KD) ranges out to 800 Meters. The US Army? meh, not so much. Well, at least in my day the Army didn't spend a whole lot of time on the KD range. But a 5.56mm (.223) won't accurately engage anything at 500 to 800 meters.

OK, stop it, Gunther! Getting too deep in the weeds here.