...As with other devices there is a small learning curve, video's posted mention finger tight assembly of the parts but as everyone has different strengths for me it is feather tight. When first assembling I found due to overtightening would make the atty be permanently connected and firing. Even with it at feather tight there is not much tolerance left for the switch, then again this is such a small gripe and after 10 mins toying around I found the perfect tightness, perhaps adding an extra O-ring to the 2 would help people at the initial assembly to avoid any confusion ?