it was made in algodoo. idk if it does work with phun(hovewer i used some very long length springs, and algodoo uses a new spring system. the springs get reseted to their normal strength(0.25) ifthere is no strength variable in the springs(algodoo uses a "constant" variable. i think that's what happened. so, don't rate it down just because it doesn't work on phun, ok?
you can set the motors on the ra2unit to "auto-brake", or just set its speed to 0 rpm, rendering it(almost)useless(it works as ballast and as an airbrake should you get too much speed)
the reason the phunbox guns don't have such fast fire rates is called sim.frequency. if you move the mechanisms too fast, then they'll overlap eachother with the default sim.frequency. that also limits the power a catridge can have(because casing or bullet will end up getting past the killer, which also happens from time to time on your weapon).
Also, make sure to remember them to reset their frequencies back to 100hz