Reaming the bores of original barrels to restore to working order . I’ve started reaming out the bores of a couple of these original barrels. As someone has mentioned (Feltwad?) the bores on old fowling pieces and trade guns are often tighter in the middle than at the ends. I have no idea how that happens.
Starting situation: the bores are of uneven diameter end to end, as much as 10 thousandths of an inch, before we consider wear, rust, and pitting. There’s a chance there’s a minor dent or two. The goal is to restore a barrel to being worthy of being used in a build.
I’m guessing that a fully equipped gunsmith in colonial times would have a boring and reaming carriage and would start by drilling such a barrel if it was rough enough and there was adequate wall thickness. If in pretty good shape it would only be reamed using a square reamer with a hickory backing, enlarged step by step by adding paper shims between the reamer and the stick.
Adjustable reamers I use adjustable reamers. These are a threaded rod with a shank having a squared end. Between nuts at each end, are blades that sit in grooves. The grooves are deeper at the tip and shallower at the shank end. As the blades are moved toward the shank, it reams a bigger hole. This is accomplished by turning the nut at the shank end lefty loosey to move it closer to the shank. Then tighten the top one down pushing the blades toward the shank end till the blades are once more pushed against the lower nut. For a barrel around 20 gauge I got an adjustable reamer with the range of 19/32” to 21/32”. 5/8” (20/32”) is pretty darn close to 20 gauge.
HSS (highly sophisticated setup): machinists, please look away or hold your noses! I stick a socket onto the square shank of the reamer. Then file a square end on a 3/8” steel rod to fit the socket. I mount the barrel in a vise at one end and rest the other in a saddle at the other end of my bench. Aligned with the bore, I have a chunk of wood with a hole in it to fit the 3/8” rod and center the reamer as it starts. Because the reamer is long, once in, it self-centers. Then I lube the bore with cutting oil or whatever I have and start cranking and advancing with a hand brace. It’s very important to take very small bites or the reamer will hang up.
Progress: at first there’s nothing but red rust being removed. I make 3 passes with the reamer before increasing the diameter. I turn both nuts about 30 degrees while in the rust removal stage. This goes on for a long time and half the bore is not even touched. Every few trips I wipe and inspect the bore. Eventually part of the bore is actually getting reamed and looking like a mirror. The shavings or frass are long and super thin. Now I might be turning the nuts to achieve a larger diameter only 15-20 degrees.
Issues : dents are a problem. Deep ring pits are a problem. The edge of the blades jams against the dent or far wall of a pit. I have to back out and re-approach with a very slow feed. Sometimes I have to decrease reamer diameter a bit. Sometimes the reamer doesnt like to be turned clockwise. It howls and jams. Then I work the brace counterclockwise. It often works better one way than the other. Who knows why?
I’m 6 hours in on a 46”, 20 gauge French trade gun barrel with a partial sighting rib, plus an hour draw filing. The bore is now pretty consistent for 3/4 of its length. There are mirror sections, grubby sections, and pitted sections. I think by the time I get the breech clean and consistent diameter end to end, it will be .640-.650 bore. I can see that it was originally kind of rough. I can see concentric grooves. It was probably drilled and reamed until the roughness was gone, and then breeched and sent for proofing. I’m guessing I’ll need another 4-6 hours. But right now it would not cut a patch if loading a round ball.
Worth it? Well, what would a hand forged fowler barrel cost me?
