Fascinating article. On the topic of freebore, I assume it has to be relatively close tolerance, not like the .410 shot shell chamber in a Bond Arms derringer shooting a .45LC where the presumed freebore might be a bit to loose to produce the freebore efffect and instead destabilizes the bullet so that the little bit of rifling at the end of the barrel does not produce the nice effect but the bullet tends to tumble, or so I have read somewhere is the problem of .45 LC out a Bond .45/.410 barrel.