COMPATIBLE CALIBERS: .308WIN, 6.5 Creedmoor, 6mm Creedmoor, 22 – 250 Rem (will work at a reduced capacity), 243 Win, 6mm XC, 260 Rem, 7mm-08 Win, 308/7.62×51 NATO, Not recommended for .300 WSM. Use a metal magazine for this caliber as the feed lips need adjustment.MDT Detachable AICS box magazines are designed to fit the MDT TAC21, ACC, ESS, LSS-XL, XRS and LSS Chassis systems, as well as many other M24 type chassis and bottom metals. Manufactured from high quality Polymer and uses a tempered steel spring. MDT AICS magazines are guaranteed to work in MDT XRS, TAC21, LSS, LSS-XL, HS3, ESS and ACC chassis systems. They do not work with the following inlets; Winchester XPC and may require fitting in Winchester Model 70. Based on customer feedback, the following systems work well with our magazines, but fitting may be required in some cases; XLR Chassis, GRS riflestocks- (Configured for AICS magazines), CDI Precision bottom metals- (Configured for AICS magazines), Pacific tool and Gauge bottom metals- (Configured for AICS magazines). MDT put their magazines through vigorous testing. They have used high quality strength polymer with a high glass content to ensure durability and strength. Although not unbreakable, they have driven over these magazines with cars and trucks which did not break them.