My idea is for a new military service sidearm. The US Army will be converting over to the more powerful XM7 rifle for combat use. This gun has higher bullet energy to deal with body armor. For support troops, the current M16 rifle and 9mm handgun will be retained. I propose replacing the M16 and 9mm armaments with a long barreled pistol firing the FK BRNO cartridge. This cartridge has a 10 mm shell case that necks down to a 7.5 mm projectile. With an 11” barrel, this round would have a muzzle velocity of about 2300 ft/sec, and 1140 ft-lbs of energy. For comparison the XM7 has 2800, the M16 has 1360, while the 9 mm has only 370 ft-lbs. This handgun would weigh 3.2 lb unloaded vs 2.2 lb for the 9 mm and 7.5 lbs for the M16. This gun can be holstered which frees up a soldiers hands plus the ammunition is lighter and more easily carried than that of the M16. I’ve attached a picture of a WW1 Luger with an 11” barrel for reference as to the proportions of the gun, which would also have a fore grip for two hand firing. I also included a picture of the FK BRNO bullet, and a depiction of what a long barreled holster might look like. This weapon would have far more lethality and about 4 time the range of the current 9 mm sidearm, and although it doesn’t quite have the lethality or range of the M16, most of these non-front line troops rarely fire their rifles, and so they are in many cases in the way.