Rotation mesh in pose mode alters shape, despite full weight

So in this photo, you see my mesh. it is normal, the way its supposed to be. now lets say i rotate the mag/whatever its called on a revolver (that center cube thing).

now theres two obvious issues here. #1, the mesh deforms as you can see, despite it having full weight paint. #2, the bone moves at a different speed than the mag, which i guess isnt the end of the world? but id like to know if that will affect anything, and how to fix it anyways. thank you for any help given.

probably the magazine gets a little weighting from all the bones.

If you select the magazine, you will see the green triangle,
there are the vertex groups that influence/deform the magazine,

you can delete all the ones that you don’t want to influence the magazine,

like this: