So you mean that I can swap the cylinder of the shooting state (having all the 6 rounds in it) with another with an animation where the rounds are falling,a nd the latter with the firts one with all 6 bullets again in it?

You can swap a mesh with a mesh and a animation with a animation you cant swap a mesh with a animated mesh.

3D animation work by moving vertices around, sometimes using bones to move these vertices.

If you move the vertices on there own around then a swapped mesh needs the same amount of vertices, if you use bones the swapped mesh needs the same amount of bone groups.

You can swap the cylinder with the 6 rounds with a cylinder with no rounds, you can also swap a bullet for a fired bullet.

Kinda "morphing" works, then. Ok: then the only solution seems the cylinder with inside the bullets already.