Living with what they give you

[D F Delozier]

So how many in here get their new shooting iron and immediately set about searching for the best load for your new revolver, powder amounts, primer brands, ball seating pressure, and the like. But few take the first basic step to even check, much less address the first most critical aspect of accuracy, ball to barrel fit. In the past Uberti has been a main offender of pushing grossly under sized cylinder chambers out the door, I have found it on my Pietta guns as well, but not to the extent of my Uberti guns.
It makes no sense to invest in load development only to send your ball rattling down the barrel due to under sized cylinder chambers, and expecting anything other than mediocre accuracy. Your ball should exit the cylinder at least at the bores groove diameter or a half to one thousands bigger.
My newest(2018) manufactured uberti NMA's chambers were all over the place size wise, and hardly any two were even the same. Went something like .4460,.4455,.4450,.4465,.4460,.4450, and a slugged .457 round ball came out the muzzle .4515 which means zero engagement of the rifling grooves, which equals crap for accuracy and tons of blow by as well as overall loss of power relative to powder used. Almost every 44 I own I've had to ream the cylinders to get a good fit, I use an adjustable hand reamer for this operation,they aren't that expensive, like 22.00 shipped this is another operation you can do your self, with a little mechanical inclination. Beware read your mic carefully, and don't do this when you're tired. My first attempt cost me a cylinder as it ended up with .461 chambers LOL now to find a 46cal NMA barrel and I could still use the cylinder.
Bottom line, if you want to realize your guns full potential, check and ream your cylinders accordingly. You don't have to settle for what ever crap the factory puts out the door.

[Hellgate]

BTDT and ended up ruining about 3 cylinders that thank God, I was able to replace and settled for the bad fit. I totally agree with you. I might have to get the reamer you mentioned. I used a .450 reamer and it worked well in the guns I got right. I had a cheap chinese vise for my drill press that got canted.

[D F Delozier]

Yeah, unless you have access to a proper milling machine, this is best done by hand, you're only removing a few thousandths in most cases. I'll find the link to the outfit I got them from, I got both sizes .36 cal and .44 cal. Be very generous with what ever cutting fluid or oil you chose, but stay away from heavy oils like motor oils, they tend to reduce the cutting efficiency. And bear in mind since these are adjustable they use a slightly tapered mandrel. Just take your time and go slow with it. Each cylinder I did took about 2_1/2 hours

[D F Delozier]

Hellgate here's a link to that reamer, I suggest you get two, cause you can't get replacement blades, that way you'll have extra blades when you break one. And if your doing probably more than one cylinder you're going to break a blade, I broke two blades out of 4 cylinders. And I didn't order two,so had to stop and wait for another order, so just get two, they're pretty cheap at this place. This is the size to do .44cal
https://www.wttool.com/index/page/pr...e+Hand+Reamers

[denster]

I can understand the fixation with having the chamber diameters match the groove diameter. Years ago, from experience with modern revolvers, I felt the same way and reamed the cylinders on my guns to match. Thing was I never noticed any increase in accuracy. An old timer pointed out to me that the soft lead ball would bump up to fill the bore. I shot a couple rounds from an unreamed revolver into a tub of water and sure enough the recovered balls were bore diameter.
If you however fell the need to ream remember that a hand reamer is only designed to take out about .001 or a little more at a pass. Trying to take out more will result in chipped blades.

[Hellgate]

Thanks! Very affordable.

[D F Delozier]

The phenomenon of "bumping up" as you call it, is know as obturation and will account for a miniscule amount of expansion on a solid round ball with typical relatively weak revolver charges, it's the principal upon which the minie ball works, but they have that thin hollow skirt on thier base, the round ball doesn't. The expansion you're finding is most likely caused by impact with your stopping medium. That's why the forcing cone is there, to guide and squeeze the ball to fill the bore completely, and it needs a larger than groove diameter ball to do it's job. This wouldn't be the first thing an "old timer" was wrong about. This has lots of benefits, better accuracy, more efficient use of powder, less leading caused by blow by gases. The only down side is a very slight increase in recoil for a given charge,caused by the better barrel seal.

[Hellgate]

Sometimes i cant get dead soft lead so a proper fit works better for a slightly harder ball.

[rodwhaincamo]

A couple of questions:

First of all, I clicked on the link but the info was vague. What are the adjustment increments?

My Pietta chambers were reamed to .449” by another, but with a .452” groove diameter I’d like to get a bit closer. However the walls are rather thin between the chambers, and I use a fairly heavy charge (weighed 33 grns of 3F Olde Eynsford or Triple 7 - both a more energetic powder) behind a bullet giving more friction/pressure than a ball. So I figured reaming to just before the bolt notches should be safe. Can these accurately be set to go to a specific depth?

How is it ensured that it reams straight?

[TruthTellers]

I'm a firm believer that a lead ball or bullet diameter should be at least equal to the chamber throat and bore groove diameter. In a percussion revolver, the ball should be a few thousandths larger than the grooves. There should be no concerns about pressures, the bearing surface of that ball in the rifling is so minimal, even conicals with their slightly larger bearing surface are still fine.

This is why I try to buy as many of my black powder revolvers from Cabela's. Any issues and I just bring it back to them to exchange for another.

[rodwhaincamo]

I create custom bullets for mine as I want a wide meplat for hunting. Because the nose is quite wide (83% on my current bullets) it’s creates a long forward driving band. And because they are so wide they’re heavy for their length. Initially I figured my Pietta would come with the slower 1:30” twist so I created a bullet that was only .460” and so about the length of a ball. It weighs 195 grns. But I found that this NMA likes 30 grns by the measure (33 grns weighed 3F Olde E) despite what projectile I shoot and so my next bullet will be a bit longer to fill in the excess space with lead. I figure this will likely weigh ~215 grns. So pressures give me a bit of concern with those thin walls.

[denster]

Originally Posted by D F Delozier

The phenomenon of "bumping up" as you call it, is know as obturation and will account for a miniscule amount of expansion on a solid round ball with typical relatively weak revolver charges, it's the principal upon which the minie ball works, but they have that thin hollow skirt on thier base, the round ball doesn't. The expansion you're finding is most likely caused by impact with your stopping medium. That's why the forcing cone is there, to guide and squeeze the ball to fill the bore completely, and it needs a larger than groove diameter ball to do it's job. This wouldn't be the first thing an "old timer" was wrong about. This has lots of benefits, better accuracy, more efficient use of powder, less leading caused by blow by gases. The only down side is a very slight increase in recoil for a given charge,caused by the better barrel seal.

Bump up or obdurate same thing. The forcing cone is there to correct slight error in cylinder alignment mostly but not to squish down over groove diameter bullets. The impact medium I was using was water I doubt that would have had much effect on obduration in any case the lands and grooves were clearly present on the periphery of the ball. Recall that I said I reamed all of my guns to groove diameter for a number of years. Gave it up because I noticed no improvement in accuracy. Sometimes "old guys" know stuff.

[Hawg]

I never reamed a chamber and I get good rifling marks on the balls.

[rodwhaincamo]

I’ve far too often read from those who compete in competitions that reaming means all the difference if the chambers are undersized. They all seem to say it makes a world of difference.

Granted I don’t compete and am not skilled enough to I want my efforts to be worthwhile in the field while hunting and my handguns are mostly meant for dealing with a downed hog where I may well want every advantage I can get as it’s typically close and fast.

Regardless I’ve intended on trying a handgun once I feel comfortable.

[Hawg]

I don't shoot much paper so this is an old pic. Distance was about 20 yards more or less. One hand, no support. Good enough for me.

[D F Delozier]

Rodwhaincamo, They are infinitely adjustable within their specific size range.
Keep in mind the blades ride on a very slightly tapered mandrel, that's how they achieve their adjustability, which means your chamber will be very slight tapered, this will become apparent to you when you start adjusting it,and checking with calipers or mic. Once you get your starting size dialed in you should take a cutting wheel and remove most the excess threads off the bottom of the mandrel, to insure you ream deep enough for even a light load. But the reamer still won't go deep enough to reach the bolt cutout in your cylinder, so don't worry about thinning that already thin point. Your actual depth of the ream only needs to be a little deeper than the balls diameter in most cases. But how ever deep you make, always try for consistency of depth as that also plays into accuracy.

[rodwhaincamo]

Thanks!