New Life
The art of barrel reboring
The rifling machine is at work on an octagonal rifle barrel. Quite a lot of
machinery and skill is required to rebore a rifle barrel.
Barrel reboring is one of those obscure but vital services to the gun trade that gives life to all manner of restoration, repair and custom gunmaking projects. This short column will hardly do the subject justice but it is important just to touch on it. Reboring, as opposed to making a rifled tube from scratch, is simply removing existing rifling and cutting new rifling in a larger caliber. Believe me, use of the word “simply” is highly misleading because the process is a complicated art that takes a lifetime to master. Which is why, important as it is, there are few successful practitioners.
The reboring process is simple in theory but equipment-rich and heavily nuanced, requiring a sophisticated understanding of machine-tool processes. A barrel is fixtured on a lathe-like machine. Then, a piloted counter-bore (a guided, square-ended drill) is run into the barrel to remove the bulk of the material between the existing bore and the new rifling.
To smooth this cut and bring it to final size, an unpiloted reamer is run through next. At this point, reborers may hand lap the barrel, a precision polishing process to smooth out imperfections and tool marks and to ascertain a consistent bore diameter all the way through—critical to good accuracy in a barrel.
Last, the tube is rifled with a special cutting head with an adjustable cutter. Multiple small, progressively deeper cuts are made until the target groove depth is achieved. The last step is to lap the finished product. The process may involve two or three precision machines with high-pressure tool lubrication systems and countless bits of specialized tooling in the form of reamers and cutters, each dedicated to a specific caliber.
This fancy .44 Special Old Model Ruger features a rebored .357 Magnum barrel.
A very popular caliber conversion.
Why?
Only someone with a hopelessly stunted imagination can fail to see the possibilities in this “simple” process. One of the most basic and common reasons to rebore is to save a gun with a rotten bore. No trouble to take a tired .30-06 and turn it into a new .35 Whelen. Other reasons would include simply wanting a .35 Whelen and not wanting to go to the trouble or expense of making and fitting a whole new barrel. Plus, what if the original barrel was some cool form like a half-round, half-octagon with a full rib seen from time to time on Continental sporting magazine rifles? One of the guys in my shop didn’t like having 300-grain .44 Mag bullets going through the target (or deer) sideways, thanks to a very slow rifling twist rate in a Marlin lever gun, so he found a .30-30 barrel and had it rebored with a faster twist to stabilize these projectiles.
Rebore projects are hardly confined to long guns. We build numerous custom revolvers every year around rebored barrels. One of the most popular revolver caliber conversions of all times, thanks to Skeeter Skelton, is turning a .357 Magnum Ruger Blackhawk into a .44 Special. Even though Ruger finally got into the act, there are countless vintage guns still seeking treatment. A particular favorite with our customers is reboring a Smith & Wesson K22 .22 rimfire barrel to .32 and modifying it to fit a Ruger Single-Six. Speaking of S&Ws, countless M28 .357s have been converted to .44 Special; many more .38/44 Heavy Duty models to .45 Colt. Consider the time and treasure required to produce an accurate replica of a pre-war Smith & Wesson 4″ round barrel with an ejector shroud and integral front sight. Thinking about the necessary contoured milling cutters alone, to say nothing of the cost, gives me a headache.
We are blessed to have a first-rate reboring operation to assist with shop projects. Founded by American Custom Gunmakers Guild member Jim Dubell, Clearwater Reboring, a division of Delta Gun Shop, offers a wide variety of reboring and relining services under the capable tutelage of Allen Baker. Jim and Allen took over the machinery of Cliff LaBounty, a real pioneer in the world of high-quality reboring, when Cliff retired in 2004. Since then Clearwater Reboring has continued in the tradition. Not only can they rebore ordinary rifle and revolver barrels, but also double rifle and combination-gun barrel sets.
As you can see, this tapered, ribbed Smith & Wesson N-frame .357 barrel
displays numerous complex compound curves and would be a nightmare
to make without specialized tooling. Easy to rebore, however.
I have a hammerless, sidelock Lancaster rook-rifle project underway that now sports a lustrous .300 Rook-caliber liner, helping to revive this lovely little gun. Finally succumbing to constant badgering from the vocal vintage single-shot rifle community, there are occasionally even tubes emerging from the shop with Henry- and Metford-style rifling. Makes one giddy at the mere thought of it. Jim and Allen have produced countless beautiful and accurate rebores for us over the years that have enabled us to offer a greater, unique variety of custom handguns. Without their skills and capabilities, a lot of gunmaking operations would be much diminished.
We are truly living in a Golden Age of custom gunmaking. Reboring is an integral part of this renaissance, offering otherwise unavailable possibilities, limited only by your imagination.
Delta Gun Shop/Clearwater Reboring
989 Bear Creek Rd.
Colville, WA 99114
(509) 684-5855
