Bore and Chamber Specs of C&B Revolvers?

[Bigslug]

Continuing my education on the charcoal burning wheelguns. . .

I decided to treat my Frankengun 1858 Remington (Armi San Marco revolver with Pietta cylinder) to the usual business of figuring out internal dimensions. I don't have my notes immediately to hand, but it went something like this:

Pin gauge down the chambers: 0.446"

Pin gauge down the barrel for bore diameter: Nothing unexpected or alarming. As I recall, about 0.01" smaller than the chamber diameter, so pretty standard.

Pounding a Hornady .457" round ball down from the muzzle for groove diameter: The barrel only took the factory graphite/powder coating off the ball with the lands, and left it untouched in the grooves. . .MAYBE compressing it only slightly down to about .455".

Even accounting for slugging up on ignition, this seems like a lot of extra space. Is this one of those BP era phenomenon where they left room in the grooves for powder residue to collect?

With my one serious outing yesterday, accuracy is pretty lackluster with either 25 or 30 grains of Goex 3F. It'll pose a serious threat to a human at 25 yards, but is more shotgun with fragments of grouping than actual grouping. Projectiles are my own cast Lyman .454" RB's with un-tumbled/unpeened sprues facing forward to the best of my ability. Barring better intel in the replies, next step will be to run them through the tumbler. I'm not doing felt wads or Crisco oversmear on the notion that none of that was done back in the day.

T.I.A.

[gunther]

You may be fighting the specifications of two different Italian manufacturers. Never heard of shooting a BP revolver without either a lubricated wad or grease over the slug. This keeps the fouling soft, and is necessary for accuracy and the ability to fire more than one cylinder full without cleaning the cylinder and barrel.
The only possible reason for not lubricating would be that you ain't gonna be able to reload with somebody shooting back. In that case, a second gun would be the ticket.

[Gtek]

Welcome to the wonderful dimensional challenging world of the Italian kit guns, and a lot of others when you get into it (Colt 2/Sig) . After going through my pile over the years I have come to the conclusion that their thinking was a soft pure ball will obturate enough for sometimes okay accuracy and keep pressures down and we will run with that. Keeping pressures down so as not to drift into issues with what ever level of metal alloy we are using in this batch. Covering for the dimension drift through a production run, so when you add up all the dimension variances and the shall we say liberal tolerances it kind of goes bang and shoots about the same most the time. I have an open top ASM that had 0.450" plus/minus cylinder with a 0.465" groove out front. I have more than a pile of them of all flavors and have really enjoyed tinkering them as the kit the guns they seem to be. I have a few that were very close and not much play time was needed, and others that need/needed just about everything to get worked or fiddled getting close to right. Being you have a top strap, the first thing I would do is slug barrel and do a few for comparison then taking that number and working from there. If the cylinder is tight in the frame what is the barrel/cylinder gap? There are threads out there about opening front of cylinder up to a depth of 0.400"-0.500" to seat a ball of a dimension equal to or one to two over groove. Then the mold equation plays into the game, that is why I now own a 0.470" RB mold now. I have several and it really does change the game.

[Bigslug]

You may be fighting the specifications of two different Italian manufacturers. Never heard of shooting a BP revolver without either a lubricated wad or grease over the slug. This keeps the fouling soft, and is necessary for accuracy and the ability to fire more than one cylinder full without cleaning the cylinder and barrel.
The only possible reason for not lubricating would be that you ain't gonna be able to reload with somebody shooting back. In that case, a second gun would be the ticket.

I was concerned about differing specs between the manufacturers, which was why I started measuring stuff in the first place, but the while the chambers of the cylinder would appear compatible with the bore diameter, the GROOVE diameter is what's puzzling. The exterior of the barrel is marked with the typical ".44 CAL", but this thing has a groove diameter closer to what one would expect on a modern .45 rifle. Without slugging again starting with a fatter chunk of lead, my impression is that if one were to use this barrel for modern cartridge practices, you might be wanting .458-.459" rifle bullets. Seemingly inappropriate for anything you'd call a .44.

From what I can piece together on lube, the cylinder face oversmear thing is a modern range practice. You aren't going to ride around on a horse or dive for cover on a battlefield in July with blobs of grease melting out of every chamber or attracting sand.

Underwads? Maybe, but lubed with what? The whole ammo stack gets compressed on loading, and lube squeeze and powder contamination would be my next concern. Fine if you're immediately shooting it out, but after marching 8-10 hours?

I've seen period Colts displayed in cases with accessories - often including a dual bullet mold casting one round ball and one conical. The conicals tend to have grooves - presumably filled by hand with the goo of choice prior to loading? Pre-fabbed flash paper cartridges were certainly a thing, but probably not assembled by a busy lieutenant with troops to supervise. And if that's your primary method of propulsion, then why all the flasks?

Of course we know that use of some form of bullet lube has its advantages, but I'm looking at battlefield practicalities of the 1860's. If there's a period method for lube with a round ball, I'm open to it.

I fired about 6-7 cylinders worth yesterday of unlubed balls. Difficulty of loading did not increase throughout the session. Barrel fouling appeared to be carbon only (no leading), and fairly easily removed with a post-session hose-down of moose milk and application of a nylon brush. Primary operational difficulty (when it wasn't fired cap jams) was rough cylinder rotation apparently caused by crud building up on the rear of the cylinder. Removing the cylinder and rubbing front and rear faces against the carpeted top of the range bench restored function well enough to continue. Since the cylinder spins fine when everything is clean, I'm left wondering if I took enough material off the ratchet surface when fitting it. As best I can tell, there is no provision for endshake on these things, so I'm hesitant to polish off any more without some tolerance guide I could check with a feeler gauge. Anybody got an Italian armorer's manual?

[Hellgate]

Slugging the bore to get groove diameter then reaming the chambers to about a thou over groove will do wonders for accuracy.

[dtknowles]

I was concerned about differing specs between the manufacturers, which was why I started measuring stuff in the first place, but the while the chambers of the cylinder would appear compatible with the bore diameter, the GROOVE diameter is what's puzzling. The exterior of the barrel is marked with the typical ".44 CAL", but this thing has a groove diameter closer to what one would expect on a modern .45 rifle. Without slugging again starting with a fatter chunk of lead, my impression is that if one were to use this barrel for modern cartridge practices, you might be wanting .458-.459" rifle bullets. Seemingly inappropriate for anything you'd call a .44.

From what I can piece together on lube, the cylinder face oversmear thing is a modern range practice. You aren't going to ride around on a horse or dive for cover on a battlefield in July with blobs of grease melting out of every chamber or attracting sand.

Underwads? Maybe, but lubed with what? The whole ammo stack gets compressed on loading, and lube squeeze and powder contamination would be my next concern. Fine if you're immediately shooting it out, but after marching 8-10 hours?

I've seen period Colts displayed in cases with accessories - often including a dual bullet mold casting one round ball and one conical. The conicals tend to have grooves - presumably filled by hand with the goo of choice prior to loading? Pre-fabbed flash paper cartridges were certainly a thing, but probably not assembled by a busy lieutenant with troops to supervise. And if that's your primary method of propulsion, then why all the flasks?

Of course we know that use of some form of bullet lube has its advantages, but I'm looking at battlefield practicalities of the 1860's. If there's a period method for lube with a round ball, I'm open to it.

I fired about 6-7 cylinders worth yesterday of unlubed balls. Difficulty of loading did not increase throughout the session. Barrel fouling appeared to be carbon only (no leading), and fairly easily removed with a post-session hose-down of moose milk and application of a nylon brush. Primary operational difficulty (when it wasn't fired cap jams) was rough cylinder rotation apparently caused by crud building up on the rear of the cylinder. Removing the cylinder and rubbing front and rear faces against the carpeted top of the range bench restored function well enough to continue. Since the cylinder spins fine when everything is clean, I'm left wondering if I took enough material off the ratchet surface when fitting it. As best I can tell, there is no provision for endshake on these things, so I'm hesitant to polish off any more without some tolerance guide I could check with a feeler gauge. Anybody got an Italian armorer's manual?

Regarding your comment:
"The exterior of the barrel is marked with the typical ".44 CAL", but this thing has a groove diameter closer to what one would expect on a modern .45 rifle. Without slugging again starting with a fatter chunk of lead, my impression is that if one were to use this barrel for modern cartridge practices, you might be wanting .458-.459" rifle bullets. Seemingly inappropriate for anything you'd call a .44."

Page 200 of my Lyman 45th edition Reloading Handbook recommends 0.470" round balls for both the Navy Arms 44 Walker Colt and the Navy Arms Second Model Dragoon. Consider it a bonus, your 44 is really a 45, that could be a good thing. Hey, my 36 cal cap and ball revolver shoots 0.380" round balls 36's are 38's and 44's are 45's. but hey, 38-40 is really a 40 caliber and 44-40 is really a 43 caliber. My 32-20 is really a 31 caliber.

If you want accuracy open up the chambers to shoot a bigger ball.

Tim

[HWooldridge]

I am in agreement that battlefield conditions during the Civil War would have dictated the most efficient and expedient loading methods. Elmer Keith claimed the old veterans he knew used a greased felt wad under a round ball, which were cut from an old hat, but someone would have to give up their valuable headwear for that to happen.

I’m pretty certain soldiers either used loose powder and ball, or they were issued nitrated paper cartridges. Grease may have been used on a conical before assembly into the cartridge but it likely wasn’t available in the field.

I have shot multiple cylinders from Colt open top revolvers without grease and they kept shooting with usable accuracy - although I haven’t done a straight up comparison of grease vs. no grease effect on groups. Remington style guns were known for getting “sticky” when they were in regular use, which was more or less cured in cartridge guns by the invention of a cylinder bushing. I haven’t done this, but suspect a Remington pattern cylinder could be modified to add a bushing that would maintain clearance.

The chamber size vs. bore issue was properly designed into period guns, but the Italians missed that boat - just like on the cylinder pins being too short for Colt replicas. Fortunately, the new ones can be tuned as discussed here and elsewhere to make a better shooter.

[Bigslug]

Thanks all!

I'll probably burn up the rest of my .457" Hornady balls to see if the "as cut" sprues on my .454's are contributing to the poor accuracy as the easiest first variable to eliminate.

An off-the-cuff thing I could try is hollow-based, flat-faced .455 Webley MKIV bullet, which is basically an ogival wadcutter. I'd have to load the cylinder off the gun, but it should tell the tale if fatter is what the gun is demanding.

I'm still curious about an endshake tolerance for a Remington, but if that pattern is known for getting stiff after 1-2 dozen rounds, that's probably just a case of the tool behaving like the tool.

The hone out may well be inevitable, but at least straightforward. The deed will probably be performed to the sound of AC/DC's Big Balls.

[Good Cheer]

The undersized chambers in Pietta's .44's is an opportunity to size the bases of soft lead .45 pistol boolits to .444.

[Gtek]

Have you tried Red and Tacky grease? Smear the rear of cylinder on hand spurs, a smear in hand window, smear in bolt window, coat inside of cylinder pin hole and finishing with a small ring around pin in front of cylinder. Back to earlier discussion in thread, did you fit cylinder to just barely fit window? You asked of factory dimensions, well, tight is tight and loose is loose. Still curious as to your B/C gap, when that gets big it changes things and not for the better. Lower velocity, gets dirty a whole bunch faster and at the worst is possible flame cutting of frame.

[HamGunner]

Italian manufacturers have changed hands and tooling so many times that there is likely no uniformity at all as to what one can expect from one period to another. But, the need for near matching sizes of cylinder chambers to barrel grooves just does not change. If the cylinder throats are far undersized, one will likely never get rid of bore leading, let alone inferior accuracy.

I have had a good number of Italian replica revolvers as well as checked out those of others and the specs are all over the place comparing different years of manufacture, let alone different manufacturers. I have improved accuracy and velocity deviation on open top revolvers by reaming out the cylinder chambers to much closer match the groove diameter of the barrels. A small amount of obturation should be expected with soft lead, but sometimes with the amount of difference in what is found in the revolvers as received right out of the box and expected to work is just not going to happen.

I suppose there could be something to be desired by shearing off a good ring from the round ball to give more bearing surface to the ball, if that ball could then seal up the bore properly. Thus, if the chamber has been reamed larger, then a larger ball would then be needed in order to shear off enough lead to provide the bore with a ball that has more bearing surface. One certainly wants to size the chambers to the bore. Makes one wonder what is going on when finding so many cylinder chambers far, far too small.

I mic'ed a couple of my recently acquired revolvers and they, being a bit fancier than the norm, likely much more effort was made to quality control in making the parts more compatible. They both fit and work like a high dollar clock. I have had to do nothing at all to either of them. They lock up tight, the yokes are the proper lengths, cylinder gaps are tight, and the timing is right on.

A 2021 model Pietta Confederate 1851 Navy .44 Cal. nickle plated with really nice engraving. Chambers .444 and a right twist .445 7-groove barrel.
A 3rd Generation Colt 1851 Navy .36 Cal. with nickle plated grip and trigger frame. Chambers .373 and left twist .375 7-groove barrel. (Uberti parts).

Both of those shoot just fine as they should. I use a .457 ball in the .44 Cal. and a .380 ball in the .36 Cal. so both balls get some decent shearing, yet still only have to obturate a very small amount to fill the grooves of the barrels.

Edit:
I do use heavy grease on the yokes and the insides around the hand, trigger, and lock and have little trouble with any type of binding even after firing 8-10 cylinders full. I normally do apply some lambs tallow/beeswax to the throats, but even without, it is still easy enough to turn the cylinder.

I might run a patch down the barrel once in a while in an attempt to maintain accuracy, but that does not seem to make much difference anyhow. Neither does the lube on the throats seem to matter that much as I have fired plenty cylinders full without and the accuracy does not seem to change. As for lubed wads, (home made punched out felt with lambs tallow/beeswax) I actually seem to get better accuracy with just the ball straight on top of the powder, plus less chance of catching the grass on fire. (It has happened to me along with paper targets set ablaze).

Sprues ? The base of a bullet is the rudder and is much more critical than the nose when it comes to accuracy, so the sprue should be placed on top. The ram should round off the sprue enough that it is not much of a factor in the accuracy I would think.

[Bigslug]

Have you tried Red and Tacky grease? Smear the rear of cylinder on hand spurs, a smear in hand window, smear in bolt window, coat inside of cylinder pin hole and finishing with a small ring around pin in front of cylinder. Back to earlier discussion in thread, did you fit cylinder to just barely fit window? You asked of factory dimensions, well, tight is tight and loose is loose. Still curious as to your B/C gap, when that gets big it changes things and not for the better. Lower velocity, gets dirty a whole bunch faster and at the worst is possible flame cutting of frame.

It's tight. No daylight visible through either end. No fore/aft play.

Lube at this point is a liberal application of undiluted Ballistol.

[Hellgate]

Bigslug,
On all my Remingtons I put bearing grease on the back of the cylinder and frame where the cylinder rubs. After each charging of the chambers with powder & ball I put a single drop of oil (I use olive but Ballistol would be great) right at the front of the cylinder where it rubs on the frame. That one drop every 5-6 shots will keep the cylinder turning all day. The drop of oil is only necessary on my Ubertis. The Euroarms Remingtons will shoot all day without gumming up.

[Bigslug]

Hellgate - thank you. Useful intel. I don't have the same level of hands-on with the Colts, but the method of the Remington's cylinder fit seems to have much in common with the AR-15 gas system - it pukes in its own food bowl and needs some form of CLP in the operating innards to allow the carbon to break down and move out of the way.

On further measuring, reaming/honing may not be a wise option.

Groove diameter of the barrel is .464". Charge holes in the cylinder are .445", and they're separated by only .05" of material. If the chambers were opened to .465", there would only be .03" worth of steel in between them. That seems a mite spooky.

So, I'm currently pondering the following:

1. Hornady .457 round balls of supposedly pure lead, and swaged so they have no sprues messing up the slipstream.

2. Tumble-peen the sprue cuts off my home-cast Lyman .454 balls so they aren't messing up the slipstream.

3. Cast said .454 balls out of a bar of Rotometals pure. They are currently made of reclaimed shotgun slugs which XRF tested at having 0.1% of both tin and antimony, the ingots from which (as I recall) ran about 8 BHN. That would certainly be fine if the chambers matched the barrel, but as things stand dimensionally, even that may not be squishy enough.

4. .45 Colt conversion cylinder that came paired with this thing. Even though it's got .452" throats, I have hollow base molds. It may not fly as intended, but it's gonna fly somehow.

[HWooldridge]

My understanding is that Remington percussion revolvers became widely available after Colt experienced their bad factory fire in 1864. The Remington design had been around for several years but was a second choice for the government to the Colt 1860 Army guns until the latter were suddenly not being produced. Of course, the 1873 Colt SAA incorporated a top strap and still fired black powder so they must have figured out how to solve the basic problem, which I believe was the incorporation of a cylinder bushing.

I've considered the cylinder chamber dilemma for some time and pondered whether a slight step would be useful at the chamber mouth. In other words, the chamber is opened only to the depth required to seat a larger diameter ball, but the area underneath that holds the powder is left alone. The length of the step only has to go half the length of a ball, so approximately .230-.240 - could probably make it .250 and call it good. This solution wouldn't work as well with conical bullets, but that formula could also be determined.

In your example, perhaps you could open the cylinder holes to .457 and see how that shoots before going any bigger.

[Woodnbow]

My understanding is that Remington percussion revolvers became widely available after Colt experienced their bad factory fire in 1864. The Remington design had been around for several years but was a second choice for the government to the Colt 1860 Army guns until the latter were suddenly not being produced. Of course, the 1873 Colt SAA incorporated a top strap and still fired black powder so they must have figured out how to solve the basic problem, which I believe was the incorporation of a cylinder bushing.

I've considered the cylinder chamber dilemma for some time and pondered whether a slight step would be useful at the chamber mouth. In other words, the chamber is opened only to the depth required to seat a larger diameter ball, but the area underneath that holds the powder is left alone. The length of the step only has to go half the length of a ball, so approximately .230-.240 - could probably make it .250 and call it good. This solution wouldn't work as well with conical bullets, but that formula could also be determined.

In your example, perhaps you could open the cylinder holes to .457 and see how that shoots before going any bigger.

You don’t need to ream the cylinder to .465. I would go to .454 and use the .457 ball. It will obdurate easily to fill the grooves and probably give you much better accuracy than the current conditions.

[indian joe]

I wrote on this last night - lost it - there a couple of keys on my board that need glued up so they wont work two or three taps while I looked at the screen and poof its gone .
anyway
we had a couple of capgunz would shoot ok with half loads and filler but hopeless with a full chamber
early italian 1860 army and a walker

so yeah heres some measurements
bore .452
chamber throat ....Army .452 .....walker .454 ----we used the supposedly right sized ball .454 and .457 which is easily found commercial or home cast
where it got interesting was groove dimensions both barrells slugged at .462----------------yep way big deep rifling, both barrells looked like they came off the same machine despite different brands on the guns. The myth of deep grooves in blackpowder gunz so the crud has somewhere to accumulate is about the dumbest idea I have heard .

anyways I did some checking around and found we could buy a nice quality round ball mold from mr Pedersoli in .464 (also makes a .462 so this tells me there is an identified problem that at least Euro shooters have encountered)
(you guys can wander into Cabelas, pick up a capgun off the shelf in the body of the store and mosey out to shoot - alls legal - NOT in Aus we a bunch worse than commifornia so - they cost a lot and are a PITA to get legal paper work - gotta work with what we have downunder)

so
I reamed the cylinders to .462 - only down far enough to seat a round ball - the Army cylinder was pretty skinny between chambers at that and the walker already took 65 grains of powder to load so neither of em needed metal removed from the powder space

we use a .464 ball - so we got 2 thou over chamber size there - ball exits at .462 which is groove size (maybe not perfect but pretty good) -
both guns now shoot neat targets with full cylinder charges - this is unusual where I hang out most target guys use light loads and filler - use a couple of grease filled egg carton wads over powder in the walker. With bog standard cowboy gun grips at 25 yards about all I can do rested is 6 in 2inches - and that is work- sometimes its a plan that dont happen! Niether of those guns is a handicap anymore with full throttle loads .

[Good Cheer]

The rifling geometry in your Pietta may depend upon when it was produced.
It makes a difference in how it interacts will chamber diameters.
The older style barrels may have lands twice the width of the grooves and the chamber diameters about half way between bore and groove diameters. And the chambers may not all be of the same diameter, may have been finish reamed to varying depths and may have some ovality that won't show up when using pin gauges.
Thoroughly check what's there to plot a path forward.

I'm expecting my .44 Pietta 1858 cylinder back any day now. Steps added to the chambers with a taper at the bottom of the counterbore. Should let me load and shoot soft cast .45 boolits without any misalignment issues or needing a stepped base.