Wow,
So much input in such a short amount of time!!! I appreciate every comment that was made, and all the information provided. I will try to expand on some of the questions brought up in the posts First and foremost, I don't intend to use the whole barrel. After some thought about logistics, , and as mentioned ballistics, I don't think something of this heaft would be much fun. As for ballistics, I am more familiar with smokeless powder, but I do know that its too much barrel. I intend to go with 1/2 the barrel.
On the subject of machining skills, I would have to say I am a beginner. I am getting relatively good at turning on a lathe, but I have major lack of skill using a mill. Primarily if I have to make anything too complex right now, I do it the old fashioned way (by hand). I also have pretty good skill in hardening steel, assuming I can generate enough heat to do the job. Right now I am restricted to small things, but in the near future I intend to build a larger "gingery furnace." (If you are not familiar with the late Mr. Gingery, I wholeheartedly suggest you guys look at what he has to offer online. He home built lots of things including lathes and high temp furnaces.) Back to the task at hand, My welding skills are nearly non-existent, I have been relearning the trade with a small light duty stick welder, but the going is slow, and I don't have access to a good one.
My knowledge of metalurgy is fairly good. If someone tells me what they want to do with a given firarm design, I can determine if its a good or bad idea. I am also familiar with the properties of various metals. On the topic of ballistics I am par in this area as I haven't done much else with black powder. I have a couple hawkens, and a colt 51' that I shoot from time to time.
My current tooling is a small beginner's smithy combo lathe/mill with a 20" center to center capacity and probably a 20" capacity mill bed. Needless to say, if something needs to be done to the barrel, its going to have to be done on something else. (I have been considering making a large simple turning apparatus lately for times like these. Fortunately, however, the barrel is tapered on the exterior already. I was pleased to see the suggestion of a shrink band for the trunion. The idea hadn't even occurred to me.
On the topic of difficulty loading the weapon with rifling: I had intended to use undersized balls, and patching in much the same way you'de use a muzzleloading rifle. I suppose I could make minie balls for it that would expand. Either way I go, I am going to have to make a mold anyway, so the shot can be as intricate or as simple as my imagination is up to developing. When I got the barrel I had originally considered making a breech weapon, as this is the type that I am most familiar with. I am a little paranoid about the government throwing me in prison for building a destructive device. While I know that if the weapon does not use a fixed cartridge it is considered a muzzleloader and not subject to NFA rules, I am concerned that a well intentioned ATF agent, or policeman may not make that distiction. After what happened to Maadi Griffin, I am inclined to believe anything can happen when it comes to gun law. After a little more careful research of the laws, I may go that route anway.
Finally, before I forget, I know that the idea I had for fasteners was not ideal. Due to my inability to weld with any confidence this was out, I hadn't thought of shrink fitting parts yet, and I really did not want to do any threading on the breech plug for reasons mentioned in the posts. All this in mind, that leaves mechanical fasteners (rivets or bolts). Though I think its reaching to try and use them to hold the gun together, and I probably won't, I have seen some pretty amazing things done with hardened bolts, and well placed rivets. The AK that I mentioned in my first post in fact is screwed together, and I am going on about its 7000th round (next time I go to the range that is.).
I had better wrap this up, I think I may have some time to start considering my blueprints, and getting some of this down on paper.
Thanks again to all who posted.