Browning 2000 semi auto shotgun

Got this from a gun show, don’t know much about it besides it was made during 73-80 by FN in Belgium. shot it however the gun do not have enough gas to load the next round after ejected the empty shell, im not sure what type of shotgun shell is requited for this to function or maybe just needs a good clean n oil, can do pick up or drop off in lower mainland or Kelowna area