Reaming the leading edge of the cylinder- I meant chamfering

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carbine85

carbine85

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I was reading an article that recommends reaming the leading edge of each cylinder to eliminate the shaving-off of the lead ring. This makes sense to me.
Why shave off the ring when you can simply get a good press tight fit without removing material?
 
Assuming all the balls you will ever use will always be within 1/10,000ths of an inch tolerance, that might work.

Shaving a ring of lead shows there are no spaces through which errant sparks can bypass the bullet and ignite the powder, causing a embarrassing "chain fire."

EDIT: Just reread. I think you mean CHAMFERING the leading edge. Ok. Some revolvers are actually made that way. Just be sure the powder is sealed.
 
If the article is talking about opening up the mouth of the cylinder, then conceivably there would be even more leading since there would be more windage from the cylinder's mouth. I wouldn't.
 
Replacement cylinders are relatively inexpensive (at least for Pietta's). I like seeing that ring but could see trying it on 1 cylinder.
 
Chamfering the cylinder mouths, if not already a factory feature, makes loading a little easier.

Actually opening up the cylinder makes no sense, potentially weakening the cylinder if done with an exuberance, adding volume to the cylinder gap, and performing no useful purpose.

Alloy no harder than BHN 8 should be used in a cap and ball revolver so that it will adequately obturate. Therefore, the discrepancy between chamber diameter and groove diameter, provided not excessive, and usually no more than .006"/.008", has no tangible impact.
 
Tommygunn said:
Assuming all the balls you will ever use will always be within 1/10,000ths of an inch tolerance, that might work.

Shaving a ring of lead shows there are no spaces through which errant sparks can bypass the bullet and ignite the powder, causing a embarrassing "chain fire."

EDIT: Just reread. I think you mean CHAMFERING the leading edge. Ok. Some revolvers are actually made that way. Just be sure the powder is sealed.
Click to expand...
I meant to say "chamfer"
 
I have a Navy arms, Uberti, 1858 that has chamfered chamber mouths,, it dates back to 1964. Don't know if it was factory or done along the way. I will say it lead to some confusion when I first got it, .375 or .380 round balls. .375 was a slip fit , judging by ram force, I had purchased a .375 rb mold then switched to 380, which lead to buying another round ball mold. As it turned out the .380s only required a moderate amount of ram force, so stayed with the .380. Of my four 36 caliber shooters its the only one to take .380 balls.
My preference would be to the square edge chambers. Using scrounged lead of varying hardness the ring shave is a good indication of a proper fitting ball. Yes I know all the mechs here will mention measuring, slugging ect, ect. ;)
 
I done it too all of mine using a rcbs deburring tool and make a chamfer and now it does make the balls press in and no shaving so that make the balls fit tighter and more lead contact to the bore when the balls go down the barrel in which makes for better accuracy!
 
midland man said:
I done it too all of mine using a rcbs deburring tool and make a chamfer and now it does make the balls press in and no shaving so that make the balls fit tighter and more lead contact to the bore when the balls go down the barrel in which makes for better accuracy!
Click to expand...

Think that may hold truth, giving one has three ball sizes to chose from in 44 caliber. .451, .454 and .457. With no more than three one thousands between sizes It would make the given sized used another one thousands. In the 32's and 36's the ball size jumps are much larger. Next gun I send off to Mike, in 44, I'll see if he offers that service.
 
RPRNY said:
Chamfering the cylinder mouths, if not already a factory feature, makes loading a little easier.

Actually opening up the cylinder makes no sense, potentially weakening the cylinder if done with an exuberance, adding volume to the cylinder gap, and performing no useful purpose.

Alloy no harder than BHN 8 should be used in a cap and ball revolver so that it will adequately obturate. Therefore, the discrepancy between chamber diameter and groove diameter, provided not excessive, and usually no more than .006"/.008", has no tangible impact.
Click to expand...

How does reaming the chambers impact the cylinder gap?

I've read from a few match shooters that reaming the chambers just a bit over bore diameter does indeed improve them.

I had my Pietta NMA opened from .446" to .449" and chamfered and I don't see any real impact. I'm no match shooter though and I don't use a rest using the 15 yd range. I'm considering opening them up further.

I have also read that the horrible difference in the Pietta .31 Pocket really requires reaming.
 
I don't see how reaming would increase the gap, chamfering on the other hand does in a way, as the distance the ball has to jump before entering the barrel is just slightly larger, though the actual measured "gap" between the end of the cylinder and the back of the forcing cone would remain the same. I ended up very slightly chamfering mine as I found that the sharp corner on some of my cylinders was not in perfect condition and was scoring the balls when pressed in. I found this out after having to pull a ball out of a chamber that wouldn't fire. I put a small chamfer on each and then polished them. They will still shave lead if the projectile is big enough. If you put a very large chamfer on their they would probably not, though you might have to do a steeper chamfer than 45deg to achieve swagging instead of shaving.
 
rodwha said:
How does reaming the chambers impact the cylinder gap?

I've read from a few match shooters that reaming the chambers just a bit over bore diameter does indeed improve them.

I had my Pietta NMA opened from .446" to .449" and chamfered and I don't see any real impact. I'm no match shooter though and I don't use a rest using the 15 yd range. I'm considering opening them up further.

I have also read that the horrible difference in the Pietta .31 Pocket really requires reaming.
Click to expand...

Reaming is removing metal. Removing metal at the interface between the chamber and the barrel increases the volume of empty space.

Further reaming, as you advocate, weakens the cylinder walls and is dangerous, particularly in older production, 70s-80s, where steel quality varied and prior to CNC machining, Monday morning specials may not be in full tolerance. You may argue to the contrary of course, but encouraging people to do so is irresponsible.
 
I'm not sure if we are on the same page. Reaming removes metal only from within the chamber, making the chamber slightly bigger in diameter along its length. slightly. it does not shorten the cylinder or remove metal from between the cylinder/barrel interface (cylinder gap) It does increase the volume of the chamber ever so slightly if that is what you mean by empty space. Any modifications to a firearm of any age should be understood by the person doing the modification and the user of the firearm. If your comfortable reaming the cylinders or chamfering their edges or working on the trigger, etc, thats on the person doing the work. I would be much more worried about someone working their trigger too much such that the gun fires unexpectedly than a modification like this. We are talking reaming the chamber diameter larger by at most 0.005" or so, which means half of that is coming off the thinner wall at the outer diameter of the cylinder. This is really really minimal, and if you do the math, I bet the reduction in strength is in the matter of a couple of %. You will probably find that the older guns actually have the correctly sized chambers, as it seems to be a more recent phenomenon where the repro companies are undersizing them for some unknown reason. The "shooters" models, etc have properly sized chambers (and are probably machined from the exact same diameter cylinder as their cheaper undersized ones)
 
I only chamfered mine using the rcbs deburing tool by hand I put a 45deg bevel on the end of each chamber so instead of shaving lead it will swag the ball in and inturn will have more lead contact to the bore! so if yours shaves the ring of lead you will lose more of the ball to fit the bore as then the ball becomes smaller in diameter and less contact with the bore!
 
As BigBoom stated there is no metal coming off of the face of the cylinder. It doesn't change the cylinder gap.

I never encouraged anyone to ream their chambers.

I have felt the same way about the thin walls between chambers, the weakest area. But I've talked with a few people who have opened there's up to 0.453" and use both a more energetic powder like I do with powder charges like mine (30 grns of 3F), and with conicals. And not just a few rounds. They have put me at ease. And as BigBoom also pointed out the match grade versions have chambers this size. It's unlikely they use different tooling to create the frames and cylinders.

Oh, and my NMA is a newer 2013 model.
 
BigBoomD said:
I'm not sure if we are on the same page. Reaming removes metal only from within the chamber, making the chamber slightly bigger in diameter along its length. slightly. it does not shorten the cylinder or remove metal from between the cylinder/barrel interface (cylinder gap) It does increase the volume of the chamber ever so slightly if that is what you mean by empty space. Any modifications to a firearm of any age should be understood by the person doing the modification and the user of the firearm. If your comfortable reaming the cylinders or chamfering their edges or working on the trigger, etc, thats on the person doing the work. I would be much more worried about someone working their trigger too much such that the gun fires unexpectedly than a modification like this. We are talking reaming the chamber diameter larger by at most 0.005" or so, which means half of that is coming off the thinner wall at the outer diameter of the cylinder. This is really really minimal, and if you do the math, I bet the reduction in strength is in the matter of a couple of %. You will probably find that the older guns actually have the correctly sized chambers, as it seems to be a more recent phenomenon where the repro companies are undersizing them for some unknown reason. The "shooters" models, etc have properly sized chambers (and are probably machined from the exact same diameter cylinder as their cheaper undersized ones)
Click to expand...

You are mistaken. Opening up the chamber mouths, beyond minimal chamfering will increase the cylinder gap, not by shortening the cylinder but by increasing the volume at the mouth of the cylinder. The impact of doing so is however absolutely minimimal. Reaming the full length of the chamber reduces the cylinder walls between the chambers and is ill advised, at best, especially when dealing with pre CNC manufacture.
 
RPRNY said:
You are mistaken. Opening up the chamber mouths, beyond minimal chamfering will increase the cylinder gap, not by shortening the cylinder but by increasing the volume at the mouth of the cylinder. The impact of doing so is however absolutely minimimal. Reaming the full length of the chamber reduces the cylinder walls between the chambers and is ill advised, at best, especially when dealing with pre CNC manufacture.
Click to expand...


I'm lost here. If cylinder gap is measured by the distance from the face of the cylinder to the beginning of the barrel how can reaming chambers adjust this?
 
Are you meaning that the diameter of the chamber, in this instance .453", is larger than the groove diameter (typically .452")?

If so this is how the ROA was produced as are the match grade guns. And this isn't called cylinder gap.
 
I think we are discussing two different things. One is chamfering, putting a small bevel on the edge of the chamber mouths; and the other is reaming, boring out the chambers to a larger diameter, typically .001 - .003" over bore size.

Chamfering is done so that the ball swages into the chamber, instead of cutting a ring of lead off the ball it swages a flat spot on the ball which gives the ball slightly more surface area with which to grip the rifling.

Reaming makes the chamber diameter larger, typically .001 - .003" larger than the grooves in the bore, so that when the ball enters the bore it swages into the rifling and creates a gas seal.
 
Chamfering is done so that the ball swages into the chamber, instead of cutting a ring of lead off the ball it swages a flat spot on the ball which gives the ball slightly more surface area with which to grip the rifling. I believe the op was referring to chamfering but for some reason it got off track!!
 
"I have an 1851 that was made in 1862. It has chamfered chambers."

That's interesting. I wonder if it might have been done originally to make it easier to seat conicals?
 
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