trevi- Thanks for the encouragement. I plan to do just that. Since I have only made one threading attempt, and crappy at that, I will certainly get some old barrels or even bar stock and at least get in some cutting the tenon and threading experience. I have made some further tweaks to my lathe and refined my indicating techniques and I have now found that my tail stock quill to be no more than 0.001" high. With the quill fully extended it dips by less than 0.0005"! I am convinced now to give chambering a go. I need to next get a 0.0001" DI for indicating the throat and also something to give a bit of float to the reamer. I like something like the Bald Eagle type because it is simple, and being simple this may reduce issues with binding. I make this work further I will also pre-drill and also bore the chamber to the reamers taper prior to actually reaming. Now, for that barrel practice, anyone have a .40-cal SS barrel that is basically scrap or can be had for a low sum?! :-)
Uhh...Nope. You need to get away from the theoretical, and get some dirt on yer hands and git some chips made. Reading about it is NOT the same as learning how to do it.
Obsessing over tools you think you need is stopping you from making progress.
Seriously. Get a couple bars of hex 12L14 and do some thread cutting. Forget the chambering, simply thread the end of the bar so it fits the action.
Too much theory, not enough hands-on!
The gains in confidence that will come from the experience, will serve you far better than the obsession with minor details that are quite frankly, past your skill level to see the difference from.
A stick of 12L14 (leaded, free machining, mild steel) is pretty cheap and increases the odds of success way the heck over the use of crappy mild steel from rebar or any other source.
Brass works too. If you have some.
Once you figure out your technique on the 12L14, try it on some old barrel stock.
Honestly, I strongly suspect that any gunsmith that you 'interviewed' about his methods , and subjected to a line of questions about the how and why that you wanted your barrel done differently than what has been working for him, is like as not going to find a reason to send you off to somewhere else. Anywhere else!
If you are not going to do the work, the pick a guy with a good rep, tell him what you want to have done and for what purpose (chamber, caliber or alternately 'with this reamer', BPCR), and let the man do what he's good at.
The less time you spend talking to him, the more time he has to get on with his work day, eh?
You are getting very very far ahead of yourself, if you wish to chamber like the big boys, without first learning to get the rest of the basics down first. Waddya gonna do if you finally cut the 'perfect' chamber and botch the threading? Or vise versa? It's all part of the process, and it can all fall apart anywhere along the way from start to finish, eh.
Y'know. Just sayin'.
Cheers
Trev