Should our Nation go to war against itself or an invading adversary the best “caliber(s)” are those that are and will be readily available which are primarily NATO authorized; hence, 22; 9mm; 223/5.56; 308/7.62; 7.62X39; 12-gauge shot shells in slug, 00-buck, #4-buck; therefore, any weapon that you choose to build or purchase as your GO-TO weapon chambered in a caliber other than these listed and should law and order completely collapse, you’ll be searching the dead for sustenance and a weapon chambered in these calibers.