My Accurate Mag for a 300 WSM (short action) measures 2.98" (the blinder plate is removed). From Accurate Mag's web site, the .308 short action max COAL is noted as 2.875" with the binder plate and 2.95" without. This is consistent with my measurements, leaving roughly 0.030" clearance between the cartridge nose and the magazine wall, i.e., 2.95" max COAL plus 0.030" clearance equals 2.98", which is what I measured for my 300 WSM mag.