Chamber diamter

[hmeier4799]

For percussion revolvers: How important is it that the diameter of the cylinder chambers be equal to or larger than the barrel groove diameter?
My Uberti Remington 36 has .3725" chambers and .379" grooves. Sometimes good groups. Other times large groups at 25 yds.

 

[Zonie]

I've been told by target shooters (and read) that they have found that having chambers equal to or slightly larger than the barrels groove diameter improves the accuracy in C&B revolvers noticeably.

That said, it is very common for the Italian replicas to have undersized chambers. Even Uberti does it with some of their guns.

Why they do this is beyond me. Several of the replicas made by both Pietta and Uberti (sometimes listed as "target" quality) have chambers that are the same diameter as the grooves in the barrels so they obviously know that it improves the guns.

Maybe if they produced all of their guns with chambers the same size or slightly larger than the groove diameters they couldn't sell their "target" models for more money? :hmm:

 

[wulf]

A long time ago I reamed all my 36 cals to 380 and
that greatly improved their accruacy.Should shoot
them more often..They are two 1836s a 51 and a 62.

 

[PeterV]

I have three .36 cal. cap and ball revolvers of Italian makes, two from the 1970' and 1980's, and the third is a CVA kit gun. All of them had cylinder bore diameters less than the barrel groove diameter. I gun smith friend of mine loaned me the reamers to ream them all to .377" diameter, and I purchased a .380 ball mold to put everything together. That made each of these pistols shoot more accurately. The .44 replicas don't seem to be as bad.

With the .36 cylinder diameters so much smaller than the barrel, I can't think the manufacturer needs to worry about barrels exploding since all that gas blowing by the loose balls in the barrel should keep any pressure down to very safe levels.

Using 12-15 grains of 3Fg powder for a charge, and filling the rest of the cylinder with a .38 spl. case full of corn meal, seating the ball just below the cylinder edge, lubing it with Crisco or SPG or the home made lubes make a fun combination. Enjoy, Peter

 

[SAJones]

I read of a fellow who claimed his original 1851 was his primary small game gun, & was very accurate. Out of curiousity, he miked the barrel & chambers, & found the chambers were larger than the barrel groove-to-groove. My original is not in that good a condition, so could not test it myself. However, an article in some long ago muzzleloading mag definately stated that chambers larger than the bore increased accuracy, & I know of a couple shooters who have reamed out their chambers. Wish I could recall the diameters that they reamed out to. Woulda tried it myself, but reamers are kinda costly & I shot a single shot in matches anyway.

 

[aap2]

Reaming out the chambers can correct another problem that sometimes exists with cheap replica revolvers: tapered cylinder bores. A tapered cylinder bore may be easy to load, but the deeper you seat the ball the smaller that it is swaged resulting in inaccuracy. Balls swaged undersize by tapered chambers can move forward during recoil inviting chainfires. A revolver with tapered chambers will often shoot more accurately with the largest powder charge or with wads/fillers; either of these prevents the ball from being seated deeply and being swaged undersize.

 

[R.M.]

An appropriate sized reamer can be had for under $20.00 from this place.
http://www.discount-tools.com/creamersindexmain1.htm