SHOP Pro2a Tactical line of 458 Socom AR-15 NR Side Charging Uppers. The 458 Socom offers similar ballistics to the legendary 45-70 but in the modern sporting AR-15 platform. It is capable of firing 250 to 600 grain bullets and is suitable for taking down medium to large game at close to moderate distances. The 458 Socom is the caliber of choice at US Armed Forces checkpoints because of its stopping power and peneration capabilities. Pro2a Tactical builds the 458 socom NRSC Uppers using the most stringent standards here in the USA and is backed by our limited lifetime warranty.