The XM6D Super Magnum (XM6DSM) is a variant of the M6D handgun created in response to Enemy shields being incredibly resistant to the M225 12.7x40mm SAPHE round. Major differences include a longer barrel, an under mounted laser/4x scope (optional), night sights, and a generally larger size.
Round: The M238 13.3x54mm SAPHE SM round is an upscaled version of the M225 SAPHE round. Due to the larger bullet, it can hold more explosive charge and is generally much more powerful. Velocity at the muzzle is <1,500 FPS, and retains that over long distances. The downside to this round is that it limits magazine capacity, standard size mags can only hold 6, and extended mags 10.