mate. what ur sayin, sounds like its no problem. thats an advantage as ur not gonna end up with spray comin out ya barrel when ya chop. im not completely sure, so could be completely wrong, but you could either have one of these bolts that prevents chooping(i think) or your pressure is really low and so prevents chopping. im prepared for a flaming, as these might well be wrong. but some expert will no doubt come up with an answer soon enough that is completely correct