I shot and chrono'd some today along with some real "out of a craft brown 20 round boxes" BH Mk262 Mod 1. The Magtech is just as accurate but faster and has a little more recoil than real BH Mk262 Mod 1.
Accuracy was roughly the same I wasn't measuring groups but it was just as accurate as BH Mk262 Mod 1. 18" gun has a 1-4x S&B Short Dot and the 14.5" gun has a 2MOA Aimpoint M4.
Chrono data:
18" BCM SS410 w/BH Mk262 Mod 1 = average velocity 2763fps, extreme spread 38fps
18" BCM SS410 w/Magtech 77gr OTM = average velocity 2778fps, extreme spread 27fps
14.5" BCM BFH Midlength w/BH Mk262 Mod 1 = 2656fps, extreme spread 49fps
14.5" BCM BFH Midlength w/Magtech 77gr OTM = 2670fps, extreme spread 22fps