On one hand I'm not a huge fan of sound gimmicks as aside from adding to the overall cost of a toy it also adds an immovable block which can impede with a toy's design/engineering (as the toy is built around this sound block). But on the other hand, looking at photos of MP36 the engineering doesn't seem to have been adversely affected by this gimmick (so it appears to be rather unobtrusive). I suspect that it's been placed on a part of a toy that was always going to be a block, like maybe inside the scope/fusion cannon.