This thread has already generated a couple PM's so I guess there is some interest and so to avoid any confusion I will answer some of the questions here.
NSW barrels are bored and reamed by Riley Smith at Longhammock Barrels in Florida. They are Excellent. Riley also puts on the initial taper to the muzzle leaving a blank area at the breach end so I can install the breachplug and have material enough to create the flats, wedding bands and etc. I ask Riley to do the taper because his machinery is faster and meaner than mine so I can hold costs down. Barrel wall thickness at the muzzle on our 20 gage is .065" which quickly increases due to the taper. Breech wall thickness at the breech is .230" (near quarter inch). They are very strong. Tolerances are exacting, +/- .002". In an experiment a couple years ago we found that 240 gr. of FFg and two patched round balls didn't blow one or even cause any dimentional differences. This would equal about a triple charge. We got bored and quit the project. By the way, we learned how hard it is to put a second ball down on top of a previously loaded one because of the air pressure between the two balls. It's hard to believe someone can double charge a muzzleloader without realizing that something is wrong.
I've seen original trade gun barrels that measured as thin as .024 at the muzzle. That's about the thickness of a matchbook cover. IMHO that is too thin to be safe. Sure they're light and handy but they can be creased or dented too easily. Imagine you have loaded your gun, leaned it against a tree, the wind blows and your gun falls over and smacks on a rock putting a crease in the barrel. Can't shoot it, can't pull the ball. Get the hack saw..
Matt, aka LaffinDog
North Star West, Inc.