View Full Version : Hmmmm, what about this? = Chamfered cylinder and countersink tool.

January 4, 2011, 09:50 PM
Poorly Fitting Bullets:

The other major factor in chain firing deals with poorly fitting bullets. Bullets not fitting the chamber walls tightly may allow hot gases from a neighboring chamber to ignite the underlying power and again, glomming on a lot of Crisco on top of the loaded chamber does no good, you'll still get a chain fire.

Some years ago, while experimenting with a Colt replica, I made a useful discovery. The minor chain firing that still occurred after using proper loading procedures could be entirely eliminated by simply removing the sharp edges at the entrance of each chamber.

As most revolvers come from the Italian factories, the openings of the cylinder chambers are machined with sharp edges. These sharp edges bite into the soft lead of the ball as the ball is started and when the ball (or conical) is rammed down, the ball is cut leaving it undersized and unsymmetrical thus creating a gap where hot gas from another chamber can enter and ignite the charge. You can vastly improve your revolver by using a countersinking tool to remove the sharp edges at the entrances of the chambers. It is easy to do and only takes a couple of minutes. Simply hold the cylinder in you left hand and carefully grind with your right hand until the sharp edges of all six chambers are removed. When finished, your cylinder chambers will be lightly ‘chamfered’ and no more than a light chamfer is needed. This operation will not disfigure your revolver in the slightest.

Chamfered cylinder and countersink tool.

Chamfering the chambers does three things for you. First: instead of shaving off a lot of lead and ending up with an undersized, unsymmetrical ball, the ball is ‘swagged’ into the hole, thus making a perfect gas tight seal (assuming no trapped powder grains). Second: because you don’t shave off so much lead, but gently swage the ball in place, the rammer force is usually less. Third: because the ball is not undersized or unsymmetrical by having been cut, it fits the bore and engages the riflings much better. When a ball fits the bore and engages the riflings properly, you get a much more accurate shot.

Taken from : http://www.geojohn.org/BlackPowder/bps2.html

January 4, 2011, 10:38 PM
This is excactly how my revolver is.

January 5, 2011, 07:47 AM
If so, any advice before I do my new 1858?
Thanks :D

January 5, 2011, 08:29 AM
I like chamfered chamber mouths - they do make starting the oversize round ball easier.

sharp edges bite into the soft lead of the ball as the ball is started and when the ball (or conical) is rammed down, the ball is cut leaving it undersized and unsymmetrical????

I don't quite see that. For that to be correct, the chamber mouth would have to be both a different shape and smaller than the body of the chamber itself. And for chamfering to correct the problem that deviation would have to be no more than a tenth of an inch deep.

Chamfering is a good idea, but the justification presented above seems far fetched to me.

Oh, and I'd highly recommend using a vise, drill press and a chamfering bit with a pilot attachment; hand reamers are very difficult to keep centered on axis. It's impossible to do with a simple countersink bit without a pilot nose, such as shown in the referenced article. You're guaranteed to end up with unsymmetric chamber mouths.

Doc Hoy
January 5, 2011, 08:46 AM
....in .44 which had unchamfered chambers (I think) due to a manufacturing oversight. I decided to chamfer the chambers thinking it would make the pistol easier to load. It didn't make much difference.

On the other hand I have an 1860 from ASP and in that pistol, the barrel is contoured such that a roundball placed on the chamber in preparation for ramming will not pass to the ramming (six oclock) position because the barrel interferes. One of the suggestions was to chamfer the chambers to permit the ball to sit lower and thus clear the barrel. I fixed it in a different way but I think that would have worked.

There is one thing I feel secure in saying about these tool bits. They have a way of grabbing the workpiece. If you decide to use it, make darned sure the cylinder absolutely will not move. If it grabs, there is not a human on the earth who has the strength to hold it in place. It will destroy the cylinder in a tenth of a second. Use a drill press. As an alternative, you might try chucking it in a handle (like a tap handle) and doing the work very carefully by hand.

Here is where I would solicit some endorsement or contradiction from others in the group who know more than I do. Lets talk about the problem that the tool seems to be intended to correct; the poorly fitting ball or bullet allowing gases to pass by. If you think about it the seal around the ball is made further down the chamber and so chamfering the rim of the chamber probably won't make the bullet seal any better. If you shave a ring all the way around the bullet, you can be relatively certain of an acceptable seal. I think that changing the shape of the rim on the chamber will not have much effect.

January 5, 2011, 09:06 AM
Granted I'm a newbie to this - but I'm having a hard time with the idea that a spark from the ignition of one chamber in the cylinder can migrate from the mouth of that chamber, through a wad of grease which completely seals the mouth of an adjacent chamber, then goes past the ball and ignites the powder charge behind it. Unless the grease sealing the chamber itself caught on fire...I just can't imagine this happening. ....

Again - I lack experience - but I'd think that with a proper dab of grease sealing the chambers - the most likely cause of a chain fire would be sparks from the caps migrating past poorly fitting caps on adjacent nipples - or on nipples left exposed when recoil caused the caps to fall off.

Doc Hoy
January 5, 2011, 09:27 AM
I am fairly certain it happened from the nipple end because of poorly fitting pinched caps.

I don't shoot a meets and my total shooting experience is probably only about ten years. So there are people here who can speak with far more authority.

But I can tell you that when it happened I was hard put to understand why it happened. I had to extensively retrace my steps. Did I leave any gaps in the grease? did I pinch all of the caps or just some of them. Did a ring shave off of every bullet? Did I accidently get an 11 cap in my 10 container? After an analysis that was as careful and complete as I could do within my own limits I arrived at the conclusion that the event occurred because of a problem at the back of the cylinder rather than at the front. It happened so fast and with so little remaining evidence that I am skeptical of anyone who can say for sure why it happened or why it happens with any certainty

In the end, all I really knew is that the ten o'clock chamber discharged along with the chamber that was in battery when I fired the pistol. And that the only thing that was not done properly was pinching the caps. (I know there are plenty of folks out there who pinch caps all of the time without problems and I am not criticising or casting fault.)

January 5, 2011, 03:58 PM
If you use "Zero flute" countersinks http://www.amazon.com/SHANK-DEGREE-SPEED-COUNTERSINK-DEBURING/dp/B002J751OM you will not have chatter, which unfortunately will quickly become a minor tragedy once it starts, because you will want to continue until it is smoothed out, and then do all the other chambers the same way (Too deep) to even them up.

Even a 45 degree chamfer will shave lead balls, so, in principle, I would want a very shallow angle that would form the lead instead of shearing it. But IMHO it's a solution for a problem that wouldn't exist with underball patches and overball lube.

If one is describing a situation where the ball is actually cut undersized by the ramming process it follows that there is a burr that is below the diameter of the chamber it seems to me, in which case if you did that to a chamber with no powder the ball would slide by it's own weight fore and aft in the chamber after pushing it in the chamber.

A very light chamfer with a hand scraper would remedy that. http://milo.com/noga-black-adjustable-deburring-scraper?aid=17

The beauty of a hand scraper is twofold, it's very controllable as to depth,and the angle you cut is totally up to you.:)

January 5, 2011, 06:17 PM
Here's mine. The chambers are sleeved. I load a .360 ball into a .357 dia.
chamber. No lead is shaved.


January 5, 2011, 09:47 PM
Interesting . . . very interesting and I for one, greatly appreciate this thread. In shooting C & B revolvers for over 40 years (my first experience was in the 60s), I'm happy and fortunate to have never had a chain fire. However, I have witnessed it several times and have to admit it made things pretty exciting for a few moments.

All the talk about "chain fires" on this forum got me to worrying quite a bit . . . after all, I'm getting older and somewhat senile. it worried me so much that I traded off several of my C & B revolvers and got me one of them new fangled cartridge guns . . . . . a nice SA New Vaquero. I'm happy to report that after quite a few rounds through her . . . I haven't had any chain fires . . . . :D

I'm bookmarking this thread as I have a new Uberti '51 Navy back at home and when I get back there in the spring, I'm sure going to look it over good and possibly see about making some improvements on it. Thanks again for the great posts, opinions and photos! :)

January 5, 2011, 10:11 PM
I chamfer all my C&B cylinder mouths. To avoid getting them asymmetrical just use a 1/2 " round grind stone. That way it doesn't matter how you hold the tool and no pilot is needed.

January 5, 2011, 10:17 PM
I'll get a 1/2" grindstone for my dremmel tool tomorrow and give it a try!
Chuck :D

January 5, 2011, 10:35 PM
Colt chamferred the chamber mouths:


January 6, 2011, 08:19 AM
having a hard time with the idea that a spark from the ignition of one chamber in the cylinder can migrate from the mouth of that chamber, through a wad of grease which completely seals the mouth of an adjacent chamber, then goes past the ball and ignites the powder charge behind it.
You are correct to think that sparks don't turn corners and migrate past grease seals. However, chain fires aren't caused by sparks, they're caused by hot combustion gases, and gasses can indeed turn corners, seek out tiny gaps and even pass through weak or thin grease seals. The only issue with a hot gas setting off powder is whether the gas has had to travel so far that it's cooled down below the powder ignition point. Sometimes it does and sometimes it doesn't!

January 6, 2011, 09:02 AM
Thanks, Mykeal, for replying. That does make more sense to me. A jet of superheated gas...I can imagine that perforating a thin seal of grease...and in that case making sure the ball has no gaps around it in the chamber seems much more important.

Another question re: chamfered chamber mouths...

- it seems to me that the process of bevelling the mouth would also increase the volume of the gap between the chamber mouth and the forcing cone of the barrel through which the gases could escape when the gun is fired. Wouldn't this lessen the force propelling the projectile?

January 7, 2011, 07:10 AM
Wouldn't this lessen the force propelling the projectile?
Yes. By a very tiny, unmeasurable amount.

January 7, 2011, 07:25 AM
To get an idea of what goes on around a revolver; B/p or modern, check out the night firings on Youtube. I first realized the extent of the combustable gases when I was shooting late on evening during a humid summer evening and the ignition was injuring or killing the multitude of mosquitoes that were gathering on my bare forearms. The table I was firing over looked like I had spilled b/p over it til I noticed that some of the flecks were still moving.:D:D:D

January 7, 2011, 10:15 AM
OK folks. Let's get back to basics.
A. Colt chamfered the mouths of the cylinders in 1862. My 1851, manufactured in 1862 does indeed have chamfered chambers.

B. If you do any cartridge reloading you have a case chamfering tool.
That tool will cut the steel of the cylinder quite nicely. 4 or 5 turns in each chamber and you have a nicely chamfered chamber. this is done with your fingers and cannot "runaway" and ruin something as a drill or Dremel mounted tool can do. I use the ultra simple Lee champfer tool on all of my 1860s.

Take the easiest way out.
The guns and engineering we are dealing with are mid 1800s in complexity. Don't over think what we are dealing with here.

January 7, 2011, 10:36 PM
I bought the Lee champfer tool on Ebay today.

Ideal Tool
January 8, 2011, 02:22 AM
Hope I'm not too late 5282jt!! Please don't try the infamous dremil tool trick!!!
that thing will either suck that tapered stone in or you will have a drunken looking chamber mouth..all wobbly all over. If you cant use a heavy drill press vise in an equally heavy & SLOW rpm press..not you average hobby tool, turn that stone by hand! Better than the stone..get some large round head BRASS screws & use lapping compound turning screw in an oblong type circular motion with hand brace & bit..you could use a var. speed drill motor but run it at lowest rpm! & check your work often! The very best way..and only because we are dealing with multiple chamfers..not like a one time bore-crown job, would be to have a good machinest or gunsmith set up cyl. in an index head on a bridgeport mill. Indicate chamber hole so concentric with spindle, then use c'bore or a large ball-end mill for a more rounded chamfer. You will have a positive stop for the tool so each chamfer will be exactly as it's neighbor & be perfectly concentric. It will be something you will be proud to show off..I guarantee you won't want anyone to see a dre-mill abortion!

January 8, 2011, 06:56 AM
I didn't find a dremmel tool stone I wanted, but after reading the post by NOZ, I decided to do it by hand, with a Lee champfer tool. I have one ordered now.
Thanks for looking out for me! :D

January 16, 2011, 11:16 AM
Would this one work? Is the quality sufficient? Thinking of ordering it to chamfer my revs, just want to make sure I have th.e proper tool. I had chamfered them before but I think I need to shave some more off and perhaps the work was not uniform.
Chamfering tool on ebay (http://cgi.ebay.com/1-2-Chamfering-Tool-Pex-al-Pex-/120608638256?pt=LH_DefaultDomain_0&hash=item1c14d5c530)

January 16, 2011, 11:26 AM
Absolutely NOT.

It looks more like a muzzle crowning tool. The pilot is .500 inches and the cutter is the opposite angle from what you would want.

January 16, 2011, 11:27 AM
Thanks Junkman, I was looking at the angle, looked all wrong.

January 16, 2011, 11:36 AM

January 16, 2011, 11:40 AM
Thank you, 5282jt. that is what I was looking for on ebay, but it eluded me and I don't think the price can get any better.