Is it recommended to bore out cylinder to barrel diameter on Italian replica revolvers?

[OldNo7]

Here are a couple of photos of what the tools look like, what a new cut and lapped cone should look like and how a ball should fit the cone...

Great pix and description -- I also have the same tools and can confirm getting great results when cleaning up a bad forcing cone.

Check out the "ring" (machining mark) of the factory forcing cone from my Ruger Old Army, before -- versus after.

Old No7

 

[Smokerr]

So I guess what I'm getting at is that I wonder if the expense and effort of reaming the cylinder is worth it. Don't forget, if you ream out the chambers you are now going to have to source larger projectiles, which means, if you cast your own, finding a mold that will work with your cylinder. If you do not cast your own, finding the right size pre-made balls might be troublesome.

That is my take, if its just for fun, why get serious about it? I get serious about my target rifles but handguns at my age? It could shoot a 1 inch group at 25 yards and I Could Not, even come close.

I just keep it in as close as needed so I don't blow the target apart. With my new setup I may be able to free hand shoot better but nothing like when I was younger. Note the electrical crimp terminal bit on the nose, that was my cheap and fast fix (I have new frames on the way).

 

[Rifleman1776]

a driven slug or cerosafe cast down bore to check groove diameter.

Spot on advice for first step. The cerosafe can be bought from Brownell's it is not real expensive and can be reused. This is a great thread with a lot of knowledgable responses. Read well, re-read and heed.

 

[SGB65]

After reading online that chamber dimensions differ from the bore on these replica revolvers, I measured my cylinder chambers on my Pietta replica Colt and Remington and sure enough my cylinder chambers are smaller than the bore. On my 1860 the cylinder chambers measure between .448" and .450" but the bore grooves of the barrel measure .458". Is it worth having a gunsmith ream these out to match the bore diameter? Has anyone here done this and experienced noticeable gains in accuracy? And why don't they come properly sized from the factory?

I had the same measurement issues on my .44 Pietta 1858. I ordered an extra regular cylinder and also a Shooters model cylinder from Dixie (which comes already at .456"). I rented a reamer online and reamed my original cylinder and the extra one. I also chamfered the chambers so the ball is swaged in, rather than shaving a ring, and works much better. I verified with a ransom rest and chrono. I get better accuracy and 1,045 fps (average of 60 fps more with 2.1 std dev). Now I have two extra cylinders that go in my belt carried cylinder pouches (that I copied from a photo of an early 1860s rig that I saw auctioned). Similar to the Pale Rider rig except flaps cover the pouches.

 

[M. De Land]

After reading online that chamber dimensions differ from the bore on these replica revolvers, I measured my cylinder chambers on my Pietta replica Colt and Remington and sure enough my cylinder chambers are smaller than the bore. On my 1860 the cylinder chambers measure between .448" and .450" but the bore grooves of the barrel measure .458". Is it worth having a gunsmith ream these out to match the bore diameter? Has anyone here done this and experienced noticeable gains in accuracy? And why don't they come properly sized from the factory?

I have found that reaming chamber mouths to groove diameter has always improve accuracy especially with bullets. The under size chamber mouths seems to work better with balls than bullets and as most reproductions all seem to come with them I'm guessing that was in Colts original design.
Would some one with an original in unaltered condition make some chamber throat and groove diameter measurements to clear this up for us.

 

[PluggedNickel]

Groove diameter in odd numbered rifling can only accurately be measured with a driven barrel slug or cerosafe cast and then measured with a tri-mic or Powley gauge which is what I use.
Virtually all chamber mouths I have measured are not uniform to each other or even perfectly round from the factory. I always check them with my set of plug gauges along with the bore (land) diameter of the barrel and then a driven slug or cerosafe cast down bore to check groove diameter.
I also lap out all tight spots found in the bore with a plug gauge which I have no idea if beneficial other than to eliminate bore leading in some cases. If the bore doesn't lead I have my doubts as to it's usefulness but it always makes be feel better to lap to a level bore at least.
I do like to lap in a bit of taper choke in rifle barrels but for hand gun a level bore is plenty good enough.

Interesting. In slugging my barrels I have not found a tight spot that would need lapped out. I’ve been lucky I guess. Do you use a plug gauge as a lap, or a brass lap you turn down to bore diameter?
I do chamfer my cylinder mouths, and also lap them for easier loading. I use Brownell’s brass 45 degree lap with their lapping compound.

 

[M. De Land]

Interesting. In slugging my barrels I have not found a tight spot that would need lapped out. I’ve been lucky I guess. Do you use a plug gauge as a lap, or a brass lap you turn down to bore diameter?
I do chamfer my cylinder mouths, and also lap them for easier loading. I use Brownell’s brass 45 degree lap with their lapping compound.

The plug gauges are precision measuring instruments and are hardened. These are used to find tight spots in bores . They will tell where the tight spot actually is in the bore.
The lead lapping slugs reveal when the tight spot is removed and then can be used to level, taper or choke a bore. I will usually have to make/pour 6-8 new lapping slugs as they wear down and the grit size is changed progressively finer up to 400 to finish. Any thing finer I have found through experience is a waste of time.
Driving a lead slug through will register the tightest spot and get close to exact ID but even dead soft pure lead has some spring back and if poured in molten has something like a 3 percent shrinkage rate.
Cerosafe shrinks initially and then will expand and be exact size after one hour so is the best for accurate ID measurements.

 

[sethwyo]

Going to just share some things that elmer keith taught us,
you may get something out of it as you consider what size of bullets to use in your six gun.

 

[sethwyo]

Remembering loading and shooting my first cap and ball revolver, the mold I had was way too big and the rb's fit in it so tight that eventually I broke the gun from the pressure on the frame from loading it, it was a brass framed open top and the bolt broke from the brass fram after several years , it was from trying to push those oversized balls that were cast out of the harder wheel weight lead.

My second cap and ball revolver really liked that size of RB and shot them very well

My first 36 Navy revolver, I didn't have a mold for it at the time, and the only round balls I could get that were close to it at the local store wor 350 diameter so I just tapped them with the butt of the revolver and that squished the rb's out a little bit making them flat on both ends but they were wide enough they would fit snugly inside the cylinder. They were accurate enough that I very quickly used up the whole box of them.

It was hard to get help from anybody back in those days because everybody I knew hated muzzleloaders and cap and ball revolvers, they all wanted modern things like Glocks and AR's and didn't have any interest in trying to help me learn about things like bullet sizes and pressures and such.
They all said I was wasting my time and now that I think about it they probably didn't know anything about such things

 

[PluggedNickel]

The plug gauges are precision measuring instruments and are hardened. These are used to find tight spots in bores . They will tell where the tight spot actually is in the bore.
The lead lapping slugs reveal when the tight spot is removed and then can be used to level, taper or choke a bore. I will usually have to make/pour 6-8 new lapping slugs as they wear down and the grit size is changed progressively finer up to 400 to finish. Any thing finer I have found through experience is a waste of time.
Driving a lead slug through will register the tightest spot and get close to exact ID but even dead soft pure lead has some spring back and if poured in molten has something like a 3 percent shrinkage rate.
Cerosafe shrinks initially and then will expand and be exact size after one hour so is the best for accurate ID measurements.

Great info. Especially the Cerosafe tip! I will try using a plug gauge through the bore and see if there are tight spots then. I just judge that by feel, when I am slugging the bore. Of course a slight restriction would not be detected my way. I wouldn’t force a plug gauge into a tight spot. Just lightly lube and slide easy and see if it goes through of its own weight. If it stops, I would send it back out the same way it went in, and check from the other end of the barrel to see how long the restriction is.
The restriction would likely be in the rifling only. And you just use a poured slug as a lap.
The forcing cones on my Uberti revolvers look great. A round ball of correct size goes in about half way with its own weight.
The Brownell’s cone reamer, and lapping tool is great! It uses the same handle that is on my chamfering tool, I also have the Lewis Lead Remover tool. It could be Pacific Tool and Die makes the forcing cone reamer for Brownell’s as well, as the chamfer and crown reamers.
My drill press is also set up with an X-Y device, makes finding centers a snap, and I have had great results using my drill press as a milling machine.