Undersized chambers in revolvers???

[bang]

Interesting thread. I have a new Pietta Remington New Model Army. I measured the chamber mouths and slugged the bore and the chamber mouths are a consistent .446, grooves .451 and lands .440. Guess I should shoot it as is (with .454 balls) before looking into reaming the chambers.

Yeah, thats just it. Not all measure under.

 

[rodwha]

Yeah, thats just it. Not all measure under.

His measured under. The grooves were .451” with .446” chambers.

 

[bang]

Was comment as to the variations in tolerances. Some do, some don't.

 

[Bad Karma]

Interesting thread. I have a new Pietta Remington New Model Army. I measured the chamber mouths and slugged the bore and the chamber mouths are a consistent .446, grooves .451 and lands .440. Guess I should shoot it as is (with .454 balls) before looking into reaming the chambers.

I would. Quite often I believe we’re trying to sort the fly specks from the pepper in the pursuit of perfection from 150 year old technology. “If it’s not broke, fix it until it is...”

 

[Rockvillerich]

I’ll be the first to admit I tend to overthink things. I like to reach a point where I feel things are ideal and/or efficient. What I know is that modern lead bullets run 0.001” over groove diameter. It’s done for a reason. I also know that there are people who compete and claim they see a noticeable difference when they ream their chambers to groove diameter or just over.

I know that soft lead will obturate, but I see there’s a point in which it’s not enough as with the Pietta .31 Rem. Not that any of the other common repros have grossly undersized chambers such as that model, but I figure the act of obturation may likely rob performance, though I have nothing substantial to back this up. Regardless I want things to be right and have things operating as well as can be within reason.

The way I’m reading your measurements is that the chambers run .451”, the grooves about .453”, and the lands about .0443”. My Pietta NMA had chambers of .446” and grooves of .4525”. Your gun has much better tolerances than my did then and still do now as my chambers have been reamed to 449”. If mine measured what yours do I wouldn’t be so quick to want them reamed as the difference isn’t that big of a deal, though I’d still consider it.

Something to consider... I've loaded .54 cal balls in a .50 rifle in a pinch, and once driven in they went down with about the same effort as a bore sized ball. Most of my C&B revolvers have needed to be reamed, and they really do shoot much better with the slightly oversized balls sealing the barrel.

 

[brawny man]

Interesting thread. Has anyone chronographed their pistol before and after honing the cylinder? Same load,same lube, loading pressure, perhaps weighed charge. Just curious.

 

[rodwha]

Something to consider... I've loaded .54 cal balls in a .50 rifle in a pinch, and once driven in they went down with about the same effort as a bore sized ball. Most of my C&B revolvers have needed to be reamed, and they really do shoot much better with the slightly oversized balls sealing the barrel.

I’ve read of people loading bore sized balls and often wondered at this. It seems that hammering it down would reform the “nose” of the ball. No? Which brings me to how accurate the oversized ball is compared to the typical patched ball load?

If a single shot or maybe a follow up shot is used, say for hunting, does one use a lubed felt wad?

And having read of full bore balls being used was this common way back when?

 

[Rockvillerich]

Interesting thread. Has anyone chronographed their pistol before and after honing the cylinder? Same load,same lube, loading pressure, perhaps weighed charge. Just curious.

Nope, never did a before and after test, but I can tell you recoil increased noticeably in the pocket Remington, and accuracy improved with all enough to convince me its worth doing. Original revolvers were made with "oversized" cylinders. An original .36 Colt with good strong rifling we slugged had a .38" bore as measured from grove to grove, and .39" cylinders.

 

[jimhallam]

Hi
Don't forget that the "modern" copies do not slug out the same as originals. The reloading of a percussion revolver using a flask was a real pain - especially in a melee -- so "cartridges" were used.
Colt in particular used paper cartridges (Leet and others made them and in England Captain Hayes's "skin cartridge" was popular) so the dimensions of the chamber are different to modern ones -- ALSO the modern ones are not tapered.
BRITISH M-L revolver chambers (e.g., the 1851 Adams) were about 2 gauges larger than the barrel gauge -- e.g., I have a pair of Tranter-Adams 38-bore (about 50cal) and the original mould is 36bore.
The idea was to (hopefully!) ensure that the balls didn't fall out due to movement when the revolver was in the holster (on the saddle). Soon the users in the Crimea realsied that that happenned too often, and one frequently finds M1851 Adams with added rammers (Wilkinson in particular favoured the Brazier rammer).

 

[Eras Gone]

Jimhallam, is right. Ready made cartridges were the norm for the US and CS military. Civilians who could afford them also relied on factory made cartridges that could be bought in any good hardware store that sold firearms. Conical bullets were also the norm for cartridges. The 1860 US Ordnance manual required a .380 conical and a .460 conical for its revolvers.

Most reproduction revolver have a chamber size that is smaller than the groove diameter of the barrel. In those cases you have to hope the force of the charge bumps up the soft lead bullet to groove diameter. Here is a video I did to show how to check your chambers to see if they match your groove diameter.

 

[jimhallam]

I am a specialist collector of "British" revolvers... especially Tranter, Deane-Harding, Adams, Beaumont-Adams and Webley "Longspurs".
Many of these are cased. It is instructive to note that particularly with the earlier revolvers that the moulds in the cases are frequently 2 gauge sizes LARGER than the nominal bore (the gauge at which the revolver was proofed) or that the chambers are two gauges LARGER than the groove diameter. --- e.g., many "54bore" revolvers (about .442") come with a 52bore mould; many 38bores with a 36bore mould.
WHY? -- seems to make sense, to ensure that the ball / bullet is firmly seated in the charge hole (chamber) and that it will then obturate to the groove diameter in the barrel.
(One problem with many early British revolvers is that the chamber is tapered --- to allow the use of the combustible paper or skin cartridge --- so trying to load with a naked ball of bullet means that the projectile seats low in the chamber -- or requires a larger diameter to avoid a long "jump" into the leade of the rifling. Some moulds are found with the base of the bullet of smaller diameter than the rest of the bullet, which suits the taper.)

As far as accuracy is concerned, the major problem with many repro revolvers is inconsistency of chamber diameter, which leads to variations in pressure... ... so it makes sense to ream them all to the same dimension.

Good shooting!

 

[Felix the Cat]

I don't know if it is has come up in previous posts, and as it refers to (breech loading shush!) arms, but Webley revolvers always had tapered chambers. The reason for this was that the .455 revolver used a Minie type bullet with a hollow base. By tapering the mouth of the chamber to be smaller than the barrel, any misalignments were catered for and the difference made up by the skirt expanding as it came out of the chamber.

Many of these pistols in the US were reamed out to use flat based bullets, which they were never designed to use..!

 

[Rudyard]

Dear Mr Hallam I have a well worn Beumont Adams & a well worn Deane Harding neither appear to be able to hit the cap and have a big gap from the cylinder to barrel hard to emagine them ever being used to that state .I also have a 36 Mannhatten Pocket its well worn yet functions correctly though that's not to defame the other two .We may have met at Bisley I was MLAGB for years but live now in NZ . I seem to recall you where involved getting the iron targets that sat behind Fultons .Not adding much to the theme but thought the Adams & Deane Harding might be of interest. Regards Rudyard

 

[bang]

My inquiries on this was answered, they are just reproductions. My take is it's a way for the manufacture to protect themselves. Should someone ream the cylinder and mess up then gets hurt then it's not their fault.
The higher end guns are built at way better tolerances. Pretty sure higher grade metal too. The only option is to live with it, precisely ream cylinder or buy higher end guns.
I have 2 rem 1858 target. They are higher end Pietta. They hit on 2 inch at 25 yards all day long and that's with old eyes. I have 6 cylinders and it doesn't matter which I use. Hits good with 454 ball or conical. Cabelas has them for 319. Extra cylinder 60 but wait till they are on sale and they usually 50. Standard rem 1858 parts fit perfect. One of my target started out a frame with barrel and sights. Picked up standard 1858 dirt cheap and stripped it for the target. Works great.

 

[zimmerstutzen]

When I last purchased a new cap and ball revolver, (a steel framed Pietta, 1858 Remington) I was more worried about differences between chambers. I measured the chamber mouths several times and was surprised that on the one I got, the chambers all measured .449. One chamber was a little out of round being almost an extra thousandth at just a shade under .450 when measured the oblong way across the chamber. I never bothered measuring the lands and grooves of the barrel. An earlier remington revolver purchase from another maker yielded chambers that varied in size by almost three thousandths.

 

[nkbj]

Did you check for uniform depths on the chambers?
I have a shorty 1851 that you can pull the cylinder, look down the chambers with it sitting on a table and tell the shallowest chamber just by looking. It is also the narrowest seeing as the reamer was tapered.