You can make a pretty good bore guide by taking a fired case, decap it, drill out the primer pocket large enough to get a cleaning rod and jag thru it. I have made them for my handi and my bolt guns. On the bolt guns you need to solder onto the rear of the case a length of 1/2" brass or copper tube to get you out past the rear of the action. Slip a proper size o-ring over the case neck to seal the chamber when you push the case in. Works just fine for me.