One method for plastic removal, the same one I sometimes use for removing Urethane, uses a Copper Pot Scrubber. They are actually "doughnut" shaped, so when you cut into it, it turns into a rolled up sheet. Take a bore brush one gauge smaller than your bore, and cut the copper the same width as the brush. Unroll the copper and roll the brush up in it. Used in a drill, it removes plastic and urethane well and won't scratch the bores.

Last edited by Ken61; 07/24/15 06:07 PM.
I prefer wood to plastic, leather to nylon, waxed cotton to Gore-Tex, and split bamboo to graphite.