450_366 If it were that easy double rifles would be as cheap a 311 Savage shotgun!

As you have found, there are lots of things that you find will not work well, regardless of how simple they seem before you try them! One of the worse ones is trying to regulate liners placed inside old shot barrels, with lop sided bushings! Liners are the absolute worse way of barreling a double rifle on a shotgun action! A double rifle made by an amateur, usually cost more than a good entry level double that shoots properly out of the box, and is ballanced properly to start with. Almost every "HOME-MADE" double rifle I've ever seen was extremely barrel heavy, and handled like a mesquite fense post, even if the work looks good, they usually don't shoot worth crap!

Asking for simple solutions to complex problems is a waste of time, because the answers are not any more simple that the problems are!

However I have seven double rifles of different chamberings! I will measure them all, and post it later, if that is what you want, but I fail to see what good it will do you. because even two doubles chambered the same way, and of the same barrel length will not regulate the same!

................................Good luck with your project!