I've been reaming my revolver cap&baller chambers for years. Example...... my Uberti Walker, which has taken down hole digging ground hogs in the farm pastures out to 200 yards and even much further is reamed to be .467 in the chambers half way down in them and has a barrel that measures .464 in the barrels grooves. I use a .472 ball for that gun and others I have. I've found that equal chambers to barrel grooves works well but.....I like the ball to come from the reamed chambers at .003's bigger than the barrels grooves. Measuring those barrel grooves diameter in cap&ballers with the seven groove barrels is a tricky one. Calipers give a small reading compared to what the barrels diameters in the grooves really are. Gotta bump up an over size ball (two rods ,one at each end on each side of the ball and hit one while not letting the other move)in the barrel and tap it out and measure it very very carefully. Why bump up a ball that is oversize fer the barrel to begin with? Well, as strange as it sounds balls that are over size to begin with and pushed into the barrels can still leave openings in the bottom of the grooves in the barrels. Put one in a barrel and look out the window with it. You'll see. Barrels with shallower grooves don't do that as much as ones with deeper grooves.
That phenomenon could probably explain some accuracy problems in cap&ballers. It seems as though the elasticity of lead lets the metal be pushed back on the ball by the lands of the barrel and actually "pull" lead out of the grooves a little when doing so. I guess having a ball at least .003 over the groove diameter helps that not to happen when the gun fires with the help of the lead obstuation.
The chambers only need to be reamed as far down as the ball will ever be seated with your min. powder charge. I remember Big Iron conveying they do the chambers at a taper for some reason and go all the way down. I don't recommend that. Doing that it's not possible to see that little step inside the chambers and ascertain that the reamer was centered well .
Ifin a pard has a drill press then he can get an economical chucking reamer to do the job. Chucking reamers come in sizes in .001 steps. Some in .0005 steps. About $12.00 fer one.
A cap&ball revolver thus reamed in the chambers to be equal to the barrels grooves or .001-.003 larger makes the danged things shoot as good or better than any cartridge gun I've ever fired. The pressure does rise fir sure. I can tell by the crack when the gun is fired. Never had any problem though even with heavy loads. I believe the chambers can be reamed even bigger than .003 over compared to the barrels grooves. Like .005-.006. You know when using just round balls.
One thing for sure. A clean barrel is a must fer accurate shooting even with blackpowder guns. The use of a proper recipe for making and using lube pills "under" the ball is the best way to be accurate with a "clean barrel" and have the gun run longer before cylinder drag. Like 200 plus shots and a clean barrel and a turning cylinder.
Not all cap&ballers need the reaming to be accurate even when the chambers are smaller than the grooves. The worst scenario for smaller chambers is when the chambers are .001-.002 smaller for some reason. A gun(cap&baller) can fire fairly accurate with chambers .004-.006 smaller than the grooves of the barrel and then have the chambers reamed to be larger and just .001-.002 smaller than the grooves and have accuracy go right to hell. I think it's the spaces between the ball in the barrel and the bottom of the grooves being smaller than if the gun had chambers .004-.006 smaller that creates ultra pressure thru the openings in the grooves gas cutting the ball.
Anywhooo...ifin ya want to use yer mill or have a good drill press and drill vise and can set up to ream center in the chambers a guy can ream his own chambers with a chucking reamer. "Use four flute-straight flute chucking reamers so the reamer doesn't try to pull it self into the hole".
The problem is setting up to be centered on the chamber. Finding the center of an existing hole. Plenty of machinists can find the spot where to drill a hole but have trouble finding the exact center of an existing hole. The Osbourn method don't work fer that either. I measure the chambers(they are not all the same on every gun wirth some slightly different in diameter a lot) and locate center by using a straight rod that's filed while chucked up and making it as close to the size of the hole as can be and still slip in. When you have a "pointer" like that so close to the size of the hole then when it can be slipped in the hole without interference when it's chucked up then it's centered well enough. The pointer has to be slipped in the chamber and not put too far past the opening of the chamber because for some odd reason a lot of the cap&ballefs come out of the box with tapered chambers gettin smaller as they go down.
I've been an advocate of properly sized chambers for a long time. Since I realized the chambers are smaller than the barrels grooves in cap&ballers. That makes fer flyers for sure like a bad crown does. I've found that the Italians make fer smaller chambers due to the fouling of subsequent shots with the blackpowder fouling. That's what I've been told anywhooo.....
Not all cap&ballers are sized small in the chambers. The Pietta Distressed finish revolvers have equal chambers to grooves as does the Pietta "Shooters Model" Remington and the Pedersoli Remington and the Pedersoli Rodgers and Spencer has chambers .001 smaller than the barrels grooves. The Uberti 1862 Pocket Police five shot has equal chambers and grooves too. The Ruger Ols Army is sized to be .003 bigger in the chambers than the barrels grooves. Well, anywhooo...
I hope to be offering cap&baller gunsmithing soon and the chambers being reamed would be one option to be done. I moved and closed my shop and haven't set back up yet. I'm actually a muzzleloader rifle man as much as a cap&baller revolver man. hee hee hee I really enjoy both. Being retired gives me the time to play more.
Hope this has been a help to anyone looking fer answers. What I post is expressing my opinions for the sake of conversing and I don't recommend that anyone change anything on their guns. You know...liability. A man makes his own decisions and does what he wants to do on his own. Right?
Hey Motorcycle Dan.........ever been around New Castle straight out on east state route 36? You know past Wal-Mart heading out past Howard and Millwood? In the little town of New Castle where that Topless Dancer place is in that old Hardware store on the main drag? You know next to where ole man what's his name parks that old tractor and them old trucks? Where the house next door to it burned down? Just down from Peggy Sues restaurant? Anywhooo.....sorry for the long post. Too much cocoa in my coffee.
