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 you utilize a standard GI mag, or a modified .458 SOCOM mag made especially for this rifle.
Below is a great photo of this longer OAL. On the left you will see our ammunition compared to a competitor's loaded ammunition on the right. As you can see, our ammunition is slightly longer due to the projectile being allowed to hang out more. We do not use the "cannelure" as a crimp point as this projectile is designed for use in a 45/70 and that crimp was intended to for that that caliber not the .458 SOCOM platform. However, since the .458 SOCOM loves this 300 Grain Hornady JHP we simply load it longer to reach it's full accuracy potential.