They use a 90 gr VLD Berger bthp match bullet, 1 in 6.5" rifling twist, 26" barrels, and start that bullet at 2800 fps. It has such a great Ballistic coefficient that it is still traveling at 1200 fps at 1000 yds, and, at 1000 yds, has the same 250 ft lbs that a .38 special has at the muzzle. Not to say that long range sniping makes any sense for SHTF, but to show you that the 223 and the AR are just as "capable" of such as any 308 auto is or ever was. The 223 AR has been beating the 308's at the 600 yd stage of the NRA Bullseye matches for over a decade now. Wake up and smell the coffee, folks. You do not need to settle for carrying half as much ammo, due to 308 weight and bulk, nor do you have to forgoe having a .22lr conversion unit for low cost, quiet practice now, or quiet foraging once SHTF. you can conceal a short barreled AR-15 on your person, not true of any 308 autorifle. you do not know what you might need to do if SHTF, so having the max number of options is best.