This is new .458 socom reloading brass. it uses a large pistol primer. 1.569-1.576 O.A.L. This a rebated .308 style head configuration, it basically a long .50 AE. It utilizes a .458″ dia. bullet. Its claim to fame is it has the velocities of a 45-70 but can be chambered in a ar-15, with a standard mag it will go single stack. Great for pig hunting and being the guy with somthing different at the range. Made in the USA.