now i am a newb to custom anything or following rules so...
couldnt you weld two barrles together to make a twin chamer barrel? to get past the dumb one barrel only rule, just machine a slot running where the two barrels meet that is paper thin down the entire thing, then just polish and hone it, would the slot effect the paintball?
i dont think it would be a gas hog because most of the air should stay in the chamber it was originally fired into (im guessing, dont flame me)
now that i thought of the whole thing i am stuck on how to lock it, maybe a pressure fit, or a powerful electromagnet?
NOTE: i am just throwing ideas out and have no idea how well or if it will work please dont flame me!!