Ovality & Variations In Chambers

[nkbj]

When checking the chambers on revolvers, have you found much in the way of ovality and variations in diameters from one chamber to the next?
In Pietta's I've typically found one or two thousandths. Sometimes more because of their use of tapered reamers and not always controlling the depth of reaming precisely enough, hence deeper insertion creates a greater diameter.

In my Ruger Old Army (the only one I've examined) there's 0.454" to 0.457", ovality and diameter variations from chamber to chamber. In my note book the cylinder was previously checked and the 0.457 diameter identified but I didn't check for ovality.
Measurements below were taken radially from the center pin and then at 90 degrees (not hunting for largest diameters). That's as much as .003 in variation in individual chambers.
(1) = 0.454/0.455
(2) = 0.454/0.456
(3) = 0.454/0.455
(4) = 0.454/0.457
(5) = 0.454/0.455
(6) = 0.454/0.456
I don't reccomember ever seeing that much ovality in Italian made chambers.

Last night I dug around in the funbox and found an old Lyman #457195. Might cast some up from soft lead today and see how they do. If I size the base down to 0.452 they will fit under the ram on the Ruger.

 

[Carbon 6]

My question would be, "does it matter if they all pass through the same forcing cone" ?

I guess the smaller ones would make the balls lighter, but by how much ?

I guess I would identify each cylinder and then do a cylinder by cylinder accuracy assessment.

 

[Carbon 6]

(1) = 0.454/0.455
(2) = 0.454/0.456
(3) = 0.454/0.455
(4) = 0.454/0.457
(5) = 0.454/0.455
(6) = 0.454/0.456

I see a pattern.

 

[hawkeye2]

"My question would be, "does it matter if they all pass through the same forcing cone" ?

It wouldn't matter so long as the ball is equal to or larger than the diameter of the bottom of the groves when the ball reaches the forcing cone.

"I guess the smaller ones would make the balls lighter, but by how much ?"

Swageing the ball down or deforming it doesn't change its weight.

"I guess I would identify each cylinder and then do a cylinder by cylinder accuracy assessment."

 

[sawyer04]

My question would be, "does it matter if they all pass through the same forcing cone" ?

I guess the smaller ones would make the balls lighter, but by how much ?

I guess I would identify each cylinder and then do a cylinder by cylinder accuracy assessment.

At first I found the lead shearing off the ball was oval while loading., even in purchased swaged ammo. It has never seemed to make a difference in performance. I think as long as the ball is shearing in a circular fashion and registers properly with the cone all would be well. This is the first time I have thought about the cylinder wells being oval. Good question.

 

[nkbj]

At first I found the lead shearing off the ball was oval while loading., even in purchased swaged ammo. It has never seemed to make a difference in performance. I think as long as the ball is shearing in a circular fashion and registers properly with the cone all would be well. This is the first time I have thought about the cylinder wells being oval. Good question.

In a Ruger? You have one like this also?

 

[hawkeye2]

I have noticed the same thing, slightly more lead shaved from one side than the other at times both using the lever and a loading stand. It has never seemed to hurt the accuracy. I've seen it in factory guns, ones I have had reamed by a first class blackpowder pistolsmith and in my Tom Ball modified Rogers & Spencer. I know in the latter cases the chambers are round and I have always assumed it was caused by the ball being pushed slightly to one side by the ram or plunger as it started into the chamber.

 

[Carbon 6]

I know in the latter cases the chambers are round and I have always assumed it was caused by the ball being pushed slightly to one side by the ram or plunger as it started into the chamber.

That was my assumption as well. Most rammers are pretty sloppy.

 

[Carbon 6]

I see a pattern.

Is anyone else intrigued by the pattern ?

 

[nkbj]

Here's a Pietta cylinder somebody messed up by trying to ream the chambers and not doing a good job. Some of the ligaments are down to as little as 0.044". Areas in the chambers vary from 0.453" to 0.459".
I put a spare cylinder in it from a swap around years ago. Works perfect. Now it's a restored to factory target model with adjustable sights.

 

[nkbj]

The messed up cylinder could make a pretty nice paper weight.

 

[Bad Karma]

The messed up cylinder could make a pretty nice paper weight.

Pen holder/paperweight...

 

[Dashing Leper]

Speedloader. Park some measured charges in each cylinder. When times comes to reload you put the fired cylinder over this one, line up the holes and flip the joined pair over like an hourglass.

 

[nkbj]

Examining the chambers' dimensions gave me an idea for the target model.
Why not have a .36 cylinder with precision .450" front ends, taper on the 1/32" step?
That way you'd have the reduced powder space and a precisely positioned stop ring.

 

[M. De Land]

I noticed and corrected this many years ago in my revolvers and it does make an incremental difference in overall accuracy enhancement. The reason is the forcing cone is having to except and swage down out of round balls ,from different clock indexed positioning, from different chamber mouth alignments.
If you have ever checked chamber alignment down bore with a range rod or better yet a small LED lamp you can generally pick up misalignment to some degree from how the chamber mouth aligns with the barrel breech.
Cylinder chamber mouths are bored and reamed in gang fixtures simultaneously and each of the cutters has plus and minus tolerances. This is why one will get small differences in the diameters with some being also out of round.
Usually in hand gun work it is not one single thing that greatly enhances accuracy potential but rather a number of small details that accumulate and c ultimate in better performance.

 

[M. De Land]

Examining the chambers' dimensions gave me an idea for the target model.
Why not have a .36 cylinder with precision .450" front ends, taper on the 1/32" step?
That way you'd have the reduced powder space and a precisely positioned stop ring.

I've seen that very thing done some where before and it proved to be a pretty good idea if I remember correctly. Say an 51 Navy rebarreled with the front of the cylinder chamber mouths rebored.

 

[Bad Karma]

Examining the chambers' dimensions gave me an idea for the target model.
Why not have a .36 cylinder with precision .450" front ends, taper on the 1/32" step?
That way you'd have the reduced powder space and a precisely positioned stop ring.

Maybe an 1860 or 1858 with liners inserted (press fit) into the chambers?

 

[Bad Karma]

I've seen that very thing done some where before and it proved to be a pretty good idea if I remember correctly. Say an 51 Navy rebarreled with the front of the cylinder chamber mouths rebored.

You’ve noted elsewhere that you ream your chambers... what kind of equipment are you using if y’all don’t mind?

 

[M. De Land]

You’ve noted elsewhere that you ream your chambers... what kind of equipment are you using if y’all don’t mind?

I've done it two ways and the first was the best. I have an early 58 Pietta Remington. After noting the out or round and different diameter cylinder chamber mouths I removed the barrel and machined a bushing that fit through the frame barrel hole very snugly with no slop on the major thread dimeter tops of the frame hole threads. I then made a very close fitting hole through the bushing center for the shank of a .450 dia. chucking reamer. The bushing housed both the reamer blades and it's shank within the portion fit to the barrel frame hole so that all was co-axially lined up. This kept everything in perfect alignment with center of the barrel boar. I then installed the cylinder back in the frame and reamed all six chambers to the same depth. This is about as close as one can get to actually line boring a fresh cylinder, indexed to the bolt notches. I took clean metal all the way around in each chamber so I wound up with jig reamed round holes, indexed to the revolver it lives in.
I had read it could also be done accurately by hand so I used this method the next time. It was not as successful as the first job . I got some chatter going in two of the holes that I don't care for but in the end with a bit of lapping to smooth things up they are round and within a few 10/1000's the same diameter. The finish is not quite as sharp as the one done with the jig bushing but I think it will prove to probably be just as accurate. I won't actually know though until I get out to the range. I did the second one to bring the ball diameter up to the barrels groove diameter.

 

[M. De Land]

You find the out of round chamber mouths by cross mic'ing each hole at 90 degrees in each chamber mouth. Plug gauges won't tell you if this condition exists.