Setting up jbl proflora m500 co2?

hi recently brought a secon Hand jbl proflora m500 kit. went to connect the regulator to the bottle last night but although I've done the nut up as tight as I can by hand the regulator is still loose and loads of movement in it. I thought this is normal as it was tight so turned the bottle on and I heard a loud gushing noise and the regulator part popped forward slightly so i quickly turned it off. so I'm guessing it was all exscapping? is this normal for this model and just turn it on and it will self lock after that?