This is the M118 version of the 7.62mm .308 M3 PMAG.
It's basically a tweaked version of the LR/SR offering fractionally longer COL, up to 2.830" (to fit M118 long range 7.62mm ammunition used by US military snipers) compared to standard 7.62x51 COL of 2.750". Handy if you want the absolute maximum COL with your rifle for homeloading.
Suitable for AR-10A and LR/SR format rifles including: Armalite AR-10A, Colt LE901-16S, CORE Rifle Systems CORE30, JP Enterprises LRP-07, KAC SR25, LaRue OBR, Les Baer .308, LMT .308 MWS, LWRCI REPR, Mega Arms MATEN, Noveske Gen III N6, POF P-308, Ruger SR-762, Ruger Precision Rifle, S&W M&P10, SIG716 and others.
Not suitable for DPMS GII designs, Armalite AR-10B, Springfield Armory M1A, Rock River Arms LAR8, FN SCAR 17S, PTR-91, HK417, M14, FN-FAL or HK91/G3 format magazines.
Magazine is fully strippable with a clip-on dust cover, is made from the usual bomb proof Magpul polymer and features a stainless steel spring and patented ant-tilt follower.
Maximum COL = 2.830" or 71.882 mm.