That shotgun that fires 4 rounds automaticly, then you need to turn the mag or something, has messed up reload now, or was it always like this?
Now you reload and once you're done, you will automaticly do the reload action again and after this you can shoot again.
Try if this happens to you as well
The M1216 is the name of the gun.
Apparently a lot of animations are looping after the patch.