Sorry, didn't mean to be a try at one ups man ship there, but your upcoming 12 bore surely did need some company.
4 bore is the biggest I have ever wanted to go with. The tubes were also from The Gun Works/Oregon Rifle Barrel Co. Have known Joe and Suzy for more years than I want to admit, and have always found them to be great people. I always turned to them for the 8 bore and 4 bore barrels I have needed. I remember several years ago at the Cascade Mountain Man Gun Show Joe had his display set up and on the end of a row of tables he had a 2 bore barrel. For some reason, that just intimidated the heck out of me. 2 bore = 1 5/16". Round ball is about 8 ounces or 3,500 grains. Then the next year, he had a rifle made out of one of those barrels. Just flat scarry!! I will shoot a 4 bore with a 400 - 450 grain charge, but no way would I shoot a 2 bore. I shot a 3 bore rifle once and that pursuaded me 4 bore was my limit. That one was a conical. Ufda!! Big whallop!! Even with a 200 grain charge.
Shane, what are you doing for the breech plug set on the 12 bore? Track used to sell a set that was made by a guy in California, if I recall correctly. I ordered up a set several years ago, but have not ever seen them delivered. Probably 10 years ago. I think the fellow was having some family health problems at the time, and no doubt lost info in the meantime. Of course, I have moved also, but he had a few years in the meantime to take care of business.
John