Based on a firearm currently used by the real French Army, the French Assault Rifle is a great custom LEGO gun for all your modern military minifigs. (Try saying that 3 times fast!) The bullpup-style of this weapon allows the gun to be compact, while still being accurate and powerful. 

Complete the modern military look with a Do Rag and Military Vest. Also check out BrickWarriors's other custom Modern Military accessories here.