Many of the Black Butterfly Ammunition .458 SOCOM rounds push the limits of the OAL. In our development, we have found that our accuracy increases with the length. We highly recommend that you utilize a standard GI Mag, Lancer Mag or a modified .458 SOCOM mag made especially for this rifle. We have also used Hexmags with fantastic results.
We also recommend that if you are using a GI Mag that you dremmel out a small half moon on the front lip of the mag. Once done, polish and buff the edges until there are no sharp edges. Reason being, the longer rounds may slam into or skip off the front lip as they feed. This could stop or slow the round down enough to cause it to fail to strip, fail to feed and in some cases a “Stove Pipe” in the action. See the picture below which illustrates this problem when the round strikes the front lip.