Author Topic: Chamber reaming (Read 1775 times)

AtlLaw · « **on:** December 02, 2011, 07:27:38 AM »

Has anyone done this to their C&B revolver?

I got thinking about it reading another thread. I had to do it to my Taurus 44Mag revolver as the chambers were way under bore diameter. It made a world of improvement in accuracy and reduced leading.

Lets say we have a revolver with a .454 bore and the cylinder mouths are .451. If we are casting RB's @ .457 would it make sense to ream the cylinder mouths out to, say for example, 455?

Or is obturasion certain enough to make this unnecessary?

Bigeasy · « **Reply #1 on:** December 02, 2011, 08:14:16 AM »

I never tried it with a black powder revolver, but it would make sense. You would think the closer the throat matched the bore, the more accuracy, and less fouling, same as any revolver. I don't know that there is much obturacion going on with a round ball at those velocities, but I could be wrong. I do know a guy who tried using hollow base conical style bullets in his 1858 Remington, figuring they would slug up to the barrel, similar to the loads used in some factory 45lc loads. His revolver did not stabilize them well, and they shot well off from the sights.

Larry

AtlLaw · « **Reply #2 on:** December 02, 2011, 09:00:39 AM »

Makes sense to me also Larry, but then I've been wrong before... $:-\$

Not really, I'm just trying to act humble!

Cornbelt · « **Reply #3 on:** December 04, 2011, 08:12:12 AM »

Wish I knew what the relationship is supposed to be between cyl mouth and forcing cone. But there is one, because Ruger replaced a lot of cyls in order to tighten the mouths. The bad ones had mouths so loose the slugs would drop clean through. The new ones won't do that, but beyond that I'm clueless.

Anybody know for sure?

gunnut69 · « **Reply #4 on:** December 31, 2011, 02:12:44 PM »

Hollow based bullets are usually the solution used for grossly oversized bores in the black powder era. Smokeless doesn't work so well. Black powder is a low velocity explosive and will easily obturate a SOFT flat based bullet. The reason black powder revolvers use oversized bullets is that they help seal the chamber against cross firing. The rammer will swage the ball down a bit and create a really effective seal. The grease applied over the seated ball mainly helps with keeping the fouling soft. The keys to the system is pure lead balls and black powders explosive nature.

coyotejoe · « **Reply #5 on:** January 01, 2012, 11:01:25 AM »

There are many things on which gunsmiths disagree but all agree that a revolver's chamber throats need to be full groove diameter of the bore or perhaps .001" over that. My first C&B revolver, a Euroarms '58 Remington, scattered balls like buckshot. I had noticed in loading it that it shaved a really thick ring of lead from a .451 ball. So I rammed a ball into an empty chamber, removed the nipple and pushed the ball back out with a small rod. That ball, after being rammed in and pushed out, would actually fall through the bore of it's own weight. I hand reamed the chambers with a 29/64" reamer, .453" and shot .457" balls and that was one of the most accurate revolvers I've ever fired. From that early experience I have since reamed the chamber of every C&B revolver .44s get the 29/64" reamer and .36s get a 3/8".

AtlLaw · « **Reply #6 on:** January 02, 2012, 06:43:33 AM »

Thanks Joe! If the numbers on this chart:
http://www.cimarron-firearms.com/boregroovetwist/bore_groove_twist-Uberti.htm
are to be believed, the grooves are pretty deep in these revolvers. your reamed diameter should give plenty of grip for the bullet, but (again, assuming the dimensions on the chart are correct) they are still under groove diameter. $:-\$

Since you didn't mention any leading problems, is it safe for me to assume the balls slugged up to groove diameter? I think it is, but I'd like your opinion.

BTW, I haven't made that call yet.

But now that the holidays are winding down I will!

Pat/Rick · « **Reply #7 on:** January 05, 2012, 07:25:13 AM »

When reaming the cylinder, is it a common practice to only go as deep as ball diameter/bullet length (conicals), or is the reaming done for the depth of the cylinder chamber? Or in the case of a stepped wall cylinder (C 1860) to the "step".

Flint · « **Reply #8 on:** January 05, 2012, 07:52:10 AM »

You don't need to go past the depth of the ball. The bolt notches are thin enough as it is. The accuracy should improve, but you willo need to use a larger ball, I use .380 balls in a 36 as it is even without a ream, as some 375 balls don't seat tightly, particularly Hornady. A 457 ball should work well in a .453 reamed chamber.
Black powder loads don't seem to lead a bore like smokeless does, I've yet to have to remove lead from a C&B gun, unless I have used a conversion cylinder with smokeless loads. Perhaps bp fouling protects the bore from leading. Another cause of leading is flame blowby melting the bullet as it passes into the forcing cone, or too hard a bullet in a conversion.

Pat/Rick · « **Reply #9 on:** January 05, 2012, 10:28:47 AM »

Thanks Flint. I kinda figured that bulet/ball depth would do it. Guess I've been luckier than most with my Pietta's. Though I don't need to ream any , its good to have info on the process. Good shooting folks!

ironball · « **Reply #10 on:** January 06, 2012, 07:24:26 PM »

I have to agree with gunnut69, but I don't think any modern replicas have grossly oversize bores, maybe only a couple thousandths over. Reaming probably won't make much difference with pure lead balls, they slug up. Since many people keep forgetting that pure lead is the best projectile for muzzleloaders and BP revolvers, they might need to resort to modern practices to shoot the harder stuff.

coyotejoe · « **Reply #11 on:** January 08, 2012, 02:16:13 AM »

Richard, I've never seen groove diameters as large as shown on the Cimmaron chart. They do vary somewhat but I expect a .36 to have a groove diameter of around .375-.376" and all the .44 I've slugged run .451-.453". I've never experienced any bore leading when shooting roundballs from C&B revolvers, if there was any it came out unnoticed when I cleaned out the powder fouling.

AtlLaw · « **Reply #12 on:** January 09, 2012, 06:44:25 AM »

Quote from: coyotejoe on January 08, 2012, 02:16:13 AM

Richard, I've never seen groove diameters as large as shown on the Cimmaron chart. ... I expect a .36 to have a groove diameter of around .375-.376" and all the .44 I've slugged run .451-.453".

I'm with you CJ. Those numbers just didn't seem right to me, but what do I know... $:-\$ But! If the barrel is around .375 or a bit bigger, and you ream the cylinders to .375 (3/8) that seems about as good as it gets!

Matter of fact I'm gonna slug mine, tonight if I have the time.

I think my throats are a pretty uniform .371 or so on the '51 and around .370 to 373 on the '61. $:-\$

do you use a pilot on the reamer?

AtlLaw · « **Reply #13 on:** January 23, 2012, 07:49:43 AM »

I finally got a chance to measure the groove diameters on my .36's last night.

The '51 was .380; the '61 was .377.

Now, if the throats are .371 on the '51, and .370 to .373 on the '61, I should think I have a problem... $:-\$

An aside here. The '51 seems to be noticeably more accurate then the '61. I wonder if the uniformity of the throats in the '51 as compared to the '61 is the reason for that.

Anyway, such a difference between throats and bore would be unacceptable to me in a cartridge revolver. Do y'all think a round ball can slug up .009?

The 3/8ths reamer would bring all the chambers to a nice uniform .375 which certainly couldn't hurt!

What about that reamer pilot Joe? $:-\$

coyotejoe · « **Reply #14 on:** January 24, 2012, 02:03:56 PM »

In blackpowder cartridges and long range ML rifles there is obturation or "slugging up" when the bullet base is squashed between the irresistible force of the exploding powder charge and the immovable object, being the inertial resistance of a long heavy bullet. That requires a relatively heavy powder charge and a heavy for diameter bullet. I really doubt that roundballs from a revolver slug up at all since they have neither the bullet mass nor the propellant charge of those rifle loads.
The good news for C&B revolvers is that the ball is pretty good at centering itself in an oversize bore and the rifling really doesn't have to have a deep bite on the ball to keep it following the lands. It is best if the ball leaves the chamber at full groove diameter but with an over powder wad to seal the gasses behind the ball there should be no bore leading and accuracy can still be pretty good even with balls somewhere between bore diameter and groove diameter.
no pilot is needed on the reamer, they usually have a tapered lead in and will self center in the chamber. What is needed is to keep both the cylinder and the reamer perfectly vertical with no great wobble. It can be done very nicely in a drill press by clamping the reamer tightly in the chuck, loosening the belt and turning the chuck by hand while a helper holds the cylinder down tightly on the table. Without a helper you can hold the cylinder in a drill vise but you really need a vise with precise cross feed so that you can center each chamber perfectly under the reamer. Turn the reamer slowly, keep it well lubed and withdraw it frequently to clear chips and check progress. Bubba could probably screw up the job but he'd almost have to be trying. After reaming each chamber I like to break the sharp edge slightly with a countersink to remove burrs from the mouth and to permit an oversize ball to swage into the chamber rather than being "cut to fit", swaging leaves a smoother surface and the compression makes a tighter fit. Good Luck and let us hear how it goes.

AtlLaw · « **Reply #15 on:** January 25, 2012, 06:45:32 AM »

Thanks Joe!

I'm gonna put a bunch of rounds down range then look at reaming the chambers.

Ya know, I probably wouldn't have thought of chucking the reamer in the drill press. $:-\$ The cylinder and rifle chamber I've done were done with a tap and die handle in my hand.

I'll bet I could set up my drill press and vise to act like a vertical lathe!

Thanks again!

ironball · « **Reply #16 on:** January 25, 2012, 07:04:00 AM »

AtlLaw, I would take coyotejoe's advice and skip the vise. Holding the cylinder in your hand allows it to center itself on the reamer better. I ream aircraft parts in this fashion where I work. It is that accurate. That said, I still doubt it's need on BP revolvers, but the whole point of this stuff is fun and games anyway, so it can't hurt.

AtlLaw · « **Reply #17 on:** January 25, 2012, 07:26:32 AM »

My Daddy always said "It's a wise man who learns from the experience of others." Thanks Iron!

And you right... none of this is really necessary but it keeps me off the streets and outa bars...

ironball · « **Reply #18 on:** January 25, 2012, 07:01:45 PM »

You can always try it first on a piece of scrap steel, with a few holes drilled undersize. A letter U drill (.368) should work.

AtlLaw · « **Reply #19 on:** January 26, 2012, 07:33:50 AM »

Another good point! I do have a tendency to jump right into things...

a little practice is a good thing.

Let me think this through here... $:-\$ If I did it alone, and held the cylinder in my left hand, turning the chuck with my right, then I would gage the alignment and (upward) pressure with my left hand. Seems like that way would make it easy to screw up alignment.

But, if I set the cylinder on the presses' base plate, holding it steady and aligned with my left hand, I would have no way lower the reamer into the cylinder and turn the chuck at the same time. I would have to turn the press on to turn the reamer... Bad Juju...

Not to mention the fact that I wouldn't be able to squirt cutting oil on the reamer...

I think I'm gonna need a couple of extra hands...

Or just shoot the darn things and not worry about what may be a non-issue... It's not like there be a troop of yankee cavalry coming through Kennesaw... AGAIN!

ironball · « **Reply #20 on:** January 26, 2012, 07:42:47 PM »

Well, I agree with "just shoot the darned things". Use pure lead. If you don't like the groups, then maybe it's time to play gunsmith.

You can run the drill press, especially if you are practicing on scrap. Just run the drill at the lowest speed. It doesn't take long to get a feel for it.

P.S. Extra hands? Why don't you get that pretty lady in your pic to help? I mean as long as she doesn't demand that you help her shop for shoes.

Hellgate · « **Reply #21 on:** February 03, 2012, 06:10:47 PM »

I reamed two Uberti Remington cylinders to .450 from .448 using the vise on the drill press and turning the reamer by hand. The vise was a POS and it got the angle wrong and I managed to ruin two cylinders. $80 bucks later for two new cylinders and I was back in business. It may well have turned out better if I had just held the cylinders down on a flat surface like has been suggested. Be careful buying cheap Chinese machinery. I reamed one 44 cal ASM Navy and that went well. I have a second unreamed 44 Navy and can tell the difference in recoil; greater on the reamed gun as the ball swages down at the forcing cone. Haven't done accuracy comparison yet.

BGRooster1 · « **Reply #22 on:** February 10, 2012, 12:02:32 PM »

I have a Pietta .31 cal. Remington pocket pistol that has chambers at .315 and bore of .323. I want to ream it but have also thought of trying a barrel off something that could be machined to fit with a proper bore.

coyotejoe · « **Reply #23 on:** February 11, 2012, 08:37:33 AM »

If you can find a good barrel for any .32 caliber centerfire revolver they tend to run .311-.315" or even a piece of military rifle barrel like 7.62 or .303 and it would not be too difficult to thread it and fit it up to a Remington. The problem with enlarging the chambers is then where do you find balls large enough.

BGRooster1 · « **Reply #24 on:** February 11, 2012, 11:30:39 AM »

CJ ,that is the reason I have held off doing the chambers for this caliber.Thanks for the thoughts on the rifle barrel options.

My .36 Euroarms Remington I bought begs for .380 balls.Where will I find that size,anyone know?

ironball · « **Reply #25 on:** February 12, 2012, 12:01:57 PM »

Quote from: BGRooster1 on February 11, 2012, 11:30:39 AM

My .36 Euroarms Remington I bought begs for .380 balls.Where will I find that size,anyone know?

Track Of The Wolf has them.