Axel,
I have a question for you and I would like your expert opinion. First of all, is there any bennefit to using the cutting bar like you did over using a chucking reamer to scoop out the troughs? One reason for my question is that I have a milling attachment for my lathe that attaches to my carriage. The vice for the milling attachment has graduations so the item being milled can be tilted to the right or left off of dead straight. Under these circumstances it seems to me that I could effectively use a chucking reamer of the proper size to do this job.
I do realise that your tool, being adjustable, would work for more and different sized shoe lumps. If I use the reamers to do these jobs it seems like the troughs would come out at the proper sizes and be somewhat smoother in the milled areas. Is there any advantage to leaving the troughs slightly rough? It looks to me like the smoother and the closer the fit up, the better the solder or brazed joint would be.
I have found by reaming out alot of monoblocks that the convergence angle of the tubes is about 1 to 1.5 degrees off dead straight for each side. This equates to roughly 2 to 3 degrees of combined convergence for each monoblock. Some people are still trying to claim that there is no built in convergence in the barrels/monoblock, but I know from experience that there is. You have to reset the angle on the holding fixture when changing over from doing one side to the next. I hope this puts that old myth down forever. Building these is hard enough without all this false information being spread around confusing people.
While we are in the myth killing mode, we might as well go on and get rid of the myth that you have to firmly hold the forend supported in your left hand and pull the gun back into your shoulder while regulating or shooting in the sights. If you don't believe this, go to Utube and watch the regulators that work for the big double rifle companies doing their shooting in. In many cases they don't even touch the forend by rather they leave it supported by a padded front fixture so that the gun can freely recoil without any hand interference from them holding it. Bob