Well the difference between a fired bullet and a non-fired bullet is that the fired one will have a dent on the back of the casing due to the hammer/pin hitting the cartridge, whereas a non-fired doesn't have a dent on the back
Yeah he just remove the fired bullets and place new ones, the casing of the bullet and the bullet itself are different so yeah, full load is no shots if you are dumb enough, it's basic guns working literally every gun ever how come he not know?