Cylinder bore

Sorry Dude · Nov 27, 2024

The cylinder bore on my 1851 Navy is .3725 and I'm having a heck of a time seating .380/.36 cal conical bullets, the kind from eras gone. I know the cylinder bore is undersized and would like to have it enlarged a few thousandths. Looking for a gunsmith/machinist that could do this, any recommendations? Thanks in advance.

Smokerr · Nov 27, 2024

Others can weight in, what I find puzzling is that the 44 (45 Cal) JD Conical is .460. It does not go into a .454 ball cylinder at all well.

It does fit the ROA decently but that was designed for a .457 ball (bullet).

So were cylinder chambers larger back in those days? In theory that is a direct copy of recovered conicals. Its unfortunate you have to get yours bored out to get to fit. The should offer some size difference.

2 shots · Nov 27, 2024

can the bullet be sized?

Sorry Dude · Nov 27, 2024

2 shots said:
can the bullet be sized?

I guess I'm sizing it as I seat it. I wonder what the original bore dimension was.

Jim in Wisconsin · Nov 27, 2024

Any machine shop could easily set up and precisely ream the cylinder holes to .375 (3/8 inch) because they will certainly have this size reamer.
Some other diameter would be a little more complicated but still not hard to do. They should only be reamed far enough down to allow the bullet to sit flush.
Ideally the bullet should end up sized to just fit the groove diameter of the barrel or very slightly over that.

Smokerr · Nov 28, 2024

I am confused by that remark. Sitting flush is not the goal. Sitting on the powder with some compression is.

You can swage bullets down but as noted, you are squeezing it down (elongating) its just takes too much force.

Again I don't know why the concical mfgs are going with .460 and the molds are the same though you can order custom ones that are not, if you want to pour your own but having done that, not something I want to go back to doing. Far too much time spent vs shooting.

Jim in Wisconsin · Nov 28, 2024

The original poster asked about enlarging his .3725 cylinder bores somewhat in order to fit .380 bullets. The bullet has to be at least flush so that the cylinder can turn. Once the bullet is in that far and then hits a small shoulder it can probably be pushed a little farther if he wants to, or else run the reamer in a little deeper. Having a shoulder there is a good thing in that makes a good seal to prevent cross firing.
I don't know anything about the Ruger Old Army bullet sizes.

Smokerr · Nov 28, 2024

Ok, still a bit of head scratching.

No insult intended, working my way through this area as well and happy to get informed if wrong.

Bullets do not need a ledge to seal. Like a ball, they should be around .003 over sized so they squeeze the band.

I don't work in the 38 caliber area so I use my referent of the 44/45s I shoot.

A purchased JD conical is .460 for the 44 offering (45 caliber as we deal with .451 or so sized bores).

That is simply too much for a chamber designed for a .454 ball. A .457 is tight, .460 is way too tight.

But for whatever reasons, Ruger went with a .457 Ball (or bullet) size for and with their chambers. I think the bore is still the same .452.

A JD Concial is a bit fiddly to slot in, but once in it presses nicely into the chamber (no ledge) and seals just fine. That is because the chamber is intended for a .457 and the .460 Conical is just right for the squeeze to get a seal.

What I don't understand is why the Concials are too big for what I assume is the standards of the originals though I could be wrong, maybe they were .456/.457 or whatever degree of variance they could get back then.

I believe I am correct in that the powder needs to be compressed a bit so your powder would have to come up above the ledge to do so and then you are dealing with possible powder to bullet bypass.

M. De Land · Nov 28, 2024

2 shots said:
can the bullet be sized?

Yes, I do so with my Walker but sized bullets are never as accurate as they are if cast to fit. The main issue is these revolvers are set up to shoot balls not conicals which is probably why the chamber mouths are all undersized to the barrel groove diameters. For some reason undersized balls shoot quite well in barrels with larger groove diameters but conicals need to be at or no more than .002 over groove diameter for best accuracy .
I've noted this in several of my percussion guns so one needs to determine wither or not you will be shooting primarily conicals before opening cylinder mouths and needing to buy a larger ball mold .

M. De Land · Nov 28, 2024

Smokerr said:
I am confused by that remark. Sitting flush is not the goal. Sitting on the powder with some compression is.

You can swage bullets down but as noted, you are squeezing it down (elongating) its just takes too much force.

Again I don't know why the concical mfgs are going with .460 and the molds are the same though you can order custom ones that are not, if you want to pour your own but having done that, not something I want to go back to doing. Far too much time spent vs shooting.

Been many years since I have not shot my own cast bullets and balls. I've cross mic'd quite a few swaged balls from both Hornady and Speer and they are no more uniform in diameter than the ones I cast from cheap ole Lee aluminum molds.
I actually really enjoy running ball or bullet out in the yard over a 55 gallon steel barrel work bench.

Sorry Dude · Nov 28, 2024

M. De Land said:
Yes, I do so with my Walker but sized bullets are never as accurate as they are if cast to fit. The main issue is these revolvers are set up to shoot balls not conicals which is probably why the chamber mouths are all undersized to the barrel groove diameters. For some reason undersized balls shoot quite well in barrels with larger groove diameters but conicals need to be at or no more than .002 over groove diameter for best accuracy .
I've noted this in several of my percussion guns so one needs to determine wither or not you will be shooting primarily conicals before opening cylinder mouths and needing to buy a larger ball mold .

Exactly! I have a cylinder I want to dedicate for shooting conicals so I want to have it bored out. I will keep the original cylinder "stock" for balls.

Smokerr · Nov 28, 2024

The main issue is these revolvers are set up to shoot balls not conicals

Do you have the dimensions of the guns to back that up?

Originally it was the opposite, but I can see it changing when the right period correct Conicals were not available until recent times.

rodwha · Nov 29, 2024

Smokerr said:
Ok, still a bit of head scratching.

No insult intended, working my way through this area as well and happy to get informed if wrong.

Bullets do not need a ledge to seal. Like a ball, they should be around .003 over sized so they squeeze the band.

I don't work in the 38 caliber area so I use my referent of the 44/45s I shoot.

A purchased JD conical is .460 for the 44 offering (45 caliber as we deal with .451 or so sized bores).

That is simply too much for a chamber designed for a .454 ball. A .457 is tight, .460 is way too tight.

But for whatever reasons, Ruger went with a .457 Ball (or bullet) size for and with their chambers. I think the bore is still the same .452.

A JD Concial is a bit fiddly to slot in, but once in it presses nicely into the chamber (no ledge) and seals just fine. That is because the chamber is intended for a .457 and the .460 Conical is just right for the squeeze to get a seal.

What I don't understand is why the Concials are too big for what I assume is the standards of the originals though I could be wrong, maybe they were .456/.457 or whatever degree of variance they could get back then.

I believe I am correct in that the powder needs to be compressed a bit so your powder would have to come up above the ledge to do so and then you are dealing with possible powder to bullet bypass.

Actually bullets don’t need to be oversized as large as a ball. A ball needs to be oversized as you are cutting a driving band, something to give it friction fit in the chamber. Bullets already have driving bands. I made the mistake of creating my .45 bullets oversized, it’s just a waste of lead.

M. De Land · Nov 29, 2024

Smokerr said:
Do you have the dimensions of the guns to back that up?

Originally it was the opposite, but I can see it changing when the right period correct Conicals were not available until recent times.

I have a Pietta 58 made in the mid 80s that I line reamed the chamber throats out to match the groove diameter and it will out shoot my ROA with balls which is what I compete with.
As far as conical shooting I have opened chamber mouths in cartridge guns to groove diameter and they have all responded positively to the alteration.
I don't really know why undersized chamber mouths tend to shoot balls more accurately than they will conicals but it seems to be the case in my limited trials from what I can see thus far in a couple revolvers. My guess is most likely radom out of square base seating of a conical as compared to the hemisphere base of a ball that doesn't care.
I also think that conical seating in a cylinder press out of the revolver might help mitigate the problem.

Smokerr · Nov 29, 2024

Actually bullets don’t need to be oversized as large as a ball. A ball needs to be oversized as you are cutting a driving band, something to give it friction fit in the chamber. Bullets already have driving bands. I made the mistake of creating my .45 bullets oversized, it’s just a waste of lead.

Emailing with Era's on the subject, the .460 seems to be a result of the narrow band at the upper end and it should squeeze down.

Have to wonder if my chambers are a bit smaller? I have measuring tools but anything under .003 variance is difficult or impossible to suss out.

rodwha · Nov 30, 2024

Smokerr said:
Emailing with Era's on the subject, the .460 seems to be a result of the narrow band at the upper end and it should squeeze down.

Have to wonder if my chambers are a bit smaller? I have measuring tools but anything under .003 variance is difficult or impossible to suss out.

Well, it makes one wonder what original chambers measured. It is beneficial to be slightly oversized in case there’s any flaws in the projectile or chamber.

My ROA chambers measured 0.453” so my next mold will drop them at probably 0.455” and sized to 0.454”. I initially followed the original Lee Ruger conical of 0.456”.

I measured my barrels and chambers by forcing a ball through. With my chambers I use a small diameter brass rod and insert through the nipple end with it removed. Then use your calipers.

I just googled them and I’m guessing you are talking about the J&D conical. It does have such a tiny front driving band so being oversized there would be beneficial.

M. De Land · Nov 30, 2024

rodwha said:
Well, it makes one wonder what original chambers measured. It is beneficial to be slightly oversized in case there’s any flaws in the projectile or chamber.

My ROA chambers measured 0.453” so my next mold will drop them at probably 0.455” and sized to 0.454”. I initially followed the original Lee Ruger conical of 0.456”.

I measured my barrels and chambers by forcing a ball through. With my chambers I use a small diameter brass rod and insert through the nipple end with it removed. Then use your calipers.

I just googled them and I’m guessing you are talking about the J&D conical. It does have such a tiny front driving band so being oversized there would be beneficial. jGet j

Get your self some cerosafe from Brownell's for making cast measuring slugs. . Quick, easy and accurate. I use it often as it is infinitely reusable.

Smokerr · Nov 30, 2024

I just googled them and I’m guessing you are talking about the J&D conical. It does have such a tiny front driving band so being oversized there would be beneficial.

That is what Eras Begone said, have to wonder if I am sub sized on the 47 Walker, really does not matter. I shot up the last of them a week or so ago. I may buy some for the Ruger and if I want, play with the 47 Walker. Seat one and drive it out and see what I have. Should do that with the Ruger as well to ensure it has a decent band.

If I try to shoot any in the 47 Walker I need to open up the loading port a tad.

SDSmlf · Nov 30, 2024

Sorry Dude said:
The cylinder bore on my 1851 Navy is .3725 and I'm having a heck of a time seating .380/.36 cal conical bullets, the kind from eras gone. I know the cylinder bore is undersized and would like to have it enlarged a few thousandths. Looking for a gunsmith/machinist that could do this, any recommendations? Thanks in advance.

Sorry Dude said:
Exactly! I have a cylinder I want to dedicate for shooting conicals so I want to have it bored out. I will keep the original cylinder "stock" for balls.

I have found that sizing the cylinder chambers to the groove diameter plus .001”-.002” has given the me the best accuracy with both roundballs and conicals in cap and ball revolvers.

What is the groove diameter of your gun? I would NOT be opening up cylinder chambers until I knew that dimension. I would then size or order sized conicals to match your gun’s chambers. I would NOT modify the gun to match any cast or swaged conical. What happens when your supplier changes sizes or there is normal lot to lot size variation over time?

Cylinder bore

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