Sure, you know .45-70, but do you know .45-70 Auto from an AR platform?
The good old black powder .45-70 Government was developed at the U.S. Army’s for use in the “Trapdoor” Springfield Model 1873 and has been a go-to round for going on 150~ years in both rifles and Gatling guns. Although the military moved on to smokeless powder after the Spanish American War in 1898, where the .30 Government in its various forms was adopted, the .45-70 was still in use by the military as the M32 blank round for line throwing rifles in the Navy and Coast Guard well through WWII and the full-rated pill with its big lead bullet has been popular with hunters and long-range target shooters since the days of Buffalo Bill.
Now, Colorado’s Phoenix Weaponry has a custom AR-10 platform that has been greatly modified to fire a similarly tweaked .45-70 round in semi-auto. The smokeless powder (48 grains of IMR 4198) loaded cartridge uses a 325-grain Hornady FTX bullet on a rebated rimmed case– the whole thing dubbed .45-70 Auto– to bring impressive performance from the AR platform of the same name.
The PW .45-70 Auto, a smokeless-loaded rebated rimmed .45-70 Government
45-70 Auto (325 gr) next to a .458 SOCOM (350 gr) and .45 ACP (230 gr)
PW gets 6 rounds of .45-70 Auto into a 10-shot Magpul AR10 mag and they advertise sub-MOA performance out of the platform.
More in my column at Guns.com