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Old August 25, 2005, 06:35 PM   #1
Steve499
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B.P. revolvers,chamber diameter/groove diameter

Looking through Dixie's catalog I noticed the chamber diameter given in the revolver specs is often smaller than the groove diameter. Uberti's .44 Walker, for instance, shows .440 land, .466 groove and .449 chamber measurements. Pietta has an 1858 Remington replica which gives .440 land and .446 for both groove and chamber diameters. I would think a revolver which has a chamber smaller than the groove diameter would tend to be less accurate than one where the ball is groove size when it enters the barrel. I seek enlightenment.
Steve.
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Old November 6, 2005, 10:40 PM   #2
gmatov
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Steve,

You don't need enlightenment.

You are right. The pistol with the chamber and groove diameter the closest will/should shoot better, full engagement with the ball. With the Rem., if you are right in the .440-.446. Hope you are, I just bought a 58 Pietta, hasn't come in yet.

Your first example shows a barrel with a ball .017 smaller than the groove dia of the barrel, tons of space for the gases to blow by, maybe flame cutting the ball as it goes, making it smaller still.

Funny that Pietta, in the body of the part owner of Pietta, has posted elsewhere that they make the ball undersize, by shaving, for liability reasons, yet makes the Rem with a ball that fits the barrel,

Topstrap? The strapless Walker handled 50-60 grains of BP without blowing up. Bad cylinder steel aside.

Ah, well, we shall see with my soon to come Rem.

Cheers,

George
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Old November 6, 2005, 11:27 PM   #3
mec
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I've found tha the Ubertis -both colt and remington- of recent manufacture run right at .450 in the chamber mouth, forcing cone and groove to groove measurements and are capable of very fine accuracy


The Piettas- including the LeMat and Remington versions, are a couple of thousanths smaller in all measurements and are also capable of fine accuracy.

Pietta Remington
Antique Remingtons generally measured .452" in the chamber mouth with compatible barrel measurements.

The only real advantage to the Pietta chambering is that it will generally provide a better grip on the .451 balls. Their .36 measurements are smaller too and are more compatible with the commercially available .375" bullets than the Ubertis. On the whole though, Uberti quality, customer service and availability of quality spare parts make are more likely to satisfy than the Pietta products.
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Old November 7, 2005, 12:00 AM   #4
MLKeith
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I have an original 1858 Remington 44 which has Civil War inspector stamps on it. It belonged to my Grandfather who bought it surplus from the war. Someone overloaded the cylinder and had one cylinder split into the adjacent cylinder bulging the OD of the cylinder sufficiently to stop it from rotating. I wanted to shoot it so I replaced the cylinder with a replica and found that the original used a .454 ball and the replicas use a .451 ball. In order to get decent accuracy I will have to ream the cylinder to about .452-453. Other than that the old gun shoots well. Timing the replica cylinder was a real chore ( I also replace the hammer, hand and springs with replica parts). I saved all the original parts in a bag if I ever wanted to go back to original. Since it was in the family I wanted it to be a shooter rather than a collector so I was not concerned with the loss of value by refurbishing it. It had not been taken care of and was in a box of old chains covered with about two inches of rust crust when I found it as a child in 1948. If you saw it today you would not believe that it had been so badly cared for. It looks great. The hammer screw is an oversize 10-28 which is a non-standard and was made for me by a machinist friend as the original was rusted through.
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Old November 7, 2005, 12:20 AM   #5
Steve499
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Those are some great groups, mec. I wanted to order a Walker or one of the dragoon models from Dixie but was sorta scared off of them by the dimensions given in the catalog. I bought a Pietta 1858 Remington and it is really a good shooter. It is probably a better shooter than I am. I wonder how much the diameters vary between individual guns of the same model and maker and how many were miked before they settled on what the various measurements were.

That would be a good test for some gun writer to do, compare accuracy to chamber/groove diameter and determine how far apart they can be and still group well.

Steve
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Old November 7, 2005, 12:39 AM   #6
Old Dragoon
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I slugged the bbl on my 2005 (BZ in the box on the frame)Pietta 58 Rem. and the BBL is.446. I mic'd the chambers and they too are .446. I used a .451 ball.
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Old November 7, 2005, 09:10 AM   #7
mec
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The engraved Remington above is a 25+ year old Pietta. It has the same small chamber/barrel measurements as the LeMat, I worked up last year. I don't know how consistent the Uberti measurements have been over time, but the recent ones-BT-BZ have all been remarkably consistent from one revolver to the next. Ive shot .451,454 and .457 balls in them with no real or detectible difference in accuracy or any significant variation in velocity averages even though the seating pressure differs considerably.

I did some sub-scientific group shooting from the bench at 50 feet (sub because I only shot a couple of groups) starting out with the belief that the .454 would out group the .451 because the smaller diameter seated so easily in the Uberti Army chambers. There was about a .5" difference in the group with the smaller ball grouping barely over one inch for five rounds and the .454 just a little bigger. If I'd done it twice, the results might have been the reverse. In any case, circa 1 inch at 50 feet is all the accuracy I can use in these things.
Here's the "worst" group:
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Old November 12, 2005, 01:43 AM   #8
gmatov
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Little late, but if you have a .445 chamber, it doesn't matter what ball you jam into it, it will still be .445. You shave it to fit the chamber, not the grooves.
If the chamber is not close to, or over, the groove size, you are shooting an undersized ball, minimal rifling grip, clearance that allows gases to blow by, maybe flame cutting the ball.

There's not a CF weapon made that has a bullet under groove size. Why do we accept C&B guns with undersized barrels?

Percussion rifle shooters won't accept them. Hell, they have to hammer the ball in to get it started in the barrel, not the cylinder chambers.

Cheers,

George
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