I  picked up a “Fire Phoenix” from Aliexpress which is a knock off of the “Fire Rat". Out of the box it has pretty poor performance, around Nerf N-strike level. The dart starts to drop around 15-20 feet. I whipped up this little spacer for the plunger tube spring that attempts to fully compress the spring when primed to get more performance out of it. I don't have a chronograph to test but I feel like it made an improvement. If you really want to get the best results I would recommend a tighter o-ring for the breach plug and for the plunger head to make a better seal. Maybe even an metal tighter fitting barrel would help.