I have 2 rifle profile barrels in 410 full choke 26 inches long. Wanting to get my double rifle lighter I got a wild hair up my **** that these 2 barrels would shave a pound off the beast if I could use these barrels with 444 brass(NOOOO not full pressure loads so don't open that can of worms). These barrel chamber a 444 perfectly and about 2 inches ahead of the brass lip the barrel starts tightening up(.412 to the muzzle for .398). The closest drill bit I have is a 27/64 @.4219. Ok I will gain a wee bit diameter for drilling but this should work for cast slugs???? am I ok thinking this way. And for rifling if I get 1 turn in the 22 inches of barrel that is drilled it should work for slow lazy slugs??? Should it be slower? For the wondering minds this application is for black powder or very light smokeless loads. What say the expierenced ones? I would talk to JES but I don't have the funds to pay attention so his work is out of the question but I have a lathe and a drill bit and plenty of time to go around!