Gears of War: Ultimate Edition

You will get this done fairly quick through playing the game.
Quickest way to to unlock this is the snub pistol as it's the fastest reloading weapon.

For those who don't know, perfect active reloads are when you push the right bumper to reload and then push it again, having the slider stop in the solid white part of the bar, you will know when you perfect active reload as your ammo will start flashing.
Simply rinse and repeat