When playing with the pump shotguns, animation issue occur when the player holds 'R' to 'check ammo', and the character's left hand is removed away from the pump to reach for the vest. However, the character can still shoot and the shotgun will pump a new shell by itself while the character is still in the 'check ammo' animation. I don't know how this will look in third person so this may cause even more visual issues for other players.
I play the shotgun a lot and don't test other guns as often, however the same issue might still apply, such as the bolt action sniper rifles.