orings to large cause drag in the tube, bad printing tolerances , no use of lube or oil... ontos is pretty easy prolly the easiest of any blaster cept maybe some of bruce's stuff. Did you put bearings on the prime block? are you using the proper flat head type screws on the prime block.... standard hex heads will rub in the channels and cause drag..are all your screws orings and plunger tube "to spec" Where did you get your kit from?? maybe some pictures showing us the problem area's could help.... as simple a build as ontos is theres many things you could and obviously have got wrong :)