boring out the rifling

I'm a machinist...but not a gunsmith. A friend of mine has an old muzzleloading rifle whose barrel is rifled. He wants to convert it to a shotgun so he wants to enlarge the barrel enuf to remove the rifling, which would bring it to about 0.550" (i.e. 28 ga).

How do I do this? Make a piloted reamer that's long enuf to go down the entire barrel? Any suggestions would be appreciated.

Scott Little

the old timey way was to craft a "long bit" ..this was a hardened square bit ,hollow ground,tapersd at both ends,& used w/ a wooden wedge & paper shims (or tapered wedge ) taking up slack as diameter increased), edge of square scraped the cut.......adjustable reamer might another way to go ...multiple passes .....they are thrded both ends ,one for a pilot , other can be used for an extension......they are also great for removing x/cess choke.....still have a pair for 20,& 12 ga.left from back when i cared (30 yrs ago) ...now i need that choke BACK that i took out of my doubles.... would think u would want the largest bore thats sensible ,w/ black powder ,,,,,,,& 28bore isnt much.....u can make it any bore that he can punch wads for ( or make a punch for ) if not using commercial wads.......a piloted D bit reamer( 1/2 reamer ,) w/ a thrded extension ,is probably best cheapest way out....
pro.rifle reborers ( to a larger CALIBER ,use a rough & 1 or 2 finish ,piloted ,fluted reamers w/ extension( at least , they used to)

best wishes
docn8as

ps .FWIW..used to "freshen " wore out rifling ,by casting a hard alloy in barrel ,around a rod,& inletting a cutter in the land of the casting & shimming it up as it scrape cut new rifling, ...then took a "long bit" & reamed to a new bore diameter w/ a brace ..recut the mold.....

forgot to mention that particularly in small ga.black powder , a recess choke is indicated to get a decent killing pattern....starting abt 1 in from end ,a gradual enlargement & gradual decrease ,maybe 2-3 in long( cut & pattern)

best wishes
docn8as

Best thing to do would be to get ahold of Cliff LaBounty at Labounty Precision Reboring. It's what he does for a living eh..