The best way to make fusion rifles viable is and has always been to make them hold a charge for 5 seconds and then vent if you don't fire "to prevent overheating", causing you to lose that round of ammo. The queen bow 15 seconds, but it generates a light effect to draw attention even if not aiming down sights. Debuffs, you can't run with them charged, which means that shotguns and sidearms still have an advantage, they make a lot of noise so you will hear them around corners. Under the current system there is nothing wrong with working them this way. Just hold the trigger to charge the system, then release to fire.