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.