Kotobukiya M.S.G MH15 Heavy Weapon Unit Selector Rifle
This release aims to fix that with more options and more GUN! Featuring interchangeable barrels, handles, and sensors, you'll be able to outfit your kits with several different types of weapon. The unused parts can even be stored on the back of Frame Arms kits using 3mm pegs, giving the appearance of storage canisters!
Whilst no scale is given it could be used with 1/144 or 1/100 scales quite successfully.