Measuring Cylinder Gap 1851 Navy

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ericb

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Hi all - What's the correct method for measuring Cylinder Gap on Uberti 1851 Navy?
 

Zonie

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Don't forget to push the cylinder back towards the hammer when your measuring.
The "hand" that rotates the cylinder is spring loaded and it will try to push the cylinder forward against the rear of the barrel.

Also, IMO, these cap and ball pistols need to have more clearance than one would expect to see on a modern pistol.

A gap of .006-.010 isn't really too great.

The larger gap is needed to allow some buildup of fouling on the face of the cylinder so it can rotate easily after a few shots have been fired.
 

denster

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Put the revolver on half cock and hold the cylinder to the rear and measure with a feeler gauge.
About a .002 is ideal. Fouling on the face of the cylinder is not a problem fouling on the arbor is in any case a close B/C gap will cut down significantly on both.
 

ericb

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Thanks Guys. Got a Uberti London Model Navy a couple years ago, and got sidetracked after initial sessions, and am now trying to whip it into shape. No stranger to BP; in fact first BP Gun I ever purchased was a Replica Arms Walker when I was 16 in the late 60's. I worked all summer to save up the $125 for it, and my Aunt had to sign for me when I picked it up. Spent my whole BP life since then primarily with Flint, and a few Percussion Muskets along the way. Am eager to get this thing up and running (first sessions were less than satisfactory, and am not afraid to ask a few Questions. Working thru the Nipple thing now - can't wait for next Range session. Have a Lee Conical Mold Question - will post that on appropriate Section -

Thanks again -

Eric
 

M. De Land

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I don't even re-barrel my smokeless revolvers that close.
Dan Wesson revolvers are the only wheel guns I have ever seen set at .002 and they usually are set up for high velocity smokeless loads for silhouette use.
Smith and Wesson and Colt D/A revolvers are recommended set at .004-.006 with a minimum of .003 and max of .008. The Same standards apply to Ruger Single actions.
With a .002 cylinder gap many of the reproduction guns would rub on the six or twelve o'clock chamber as most arbors and base pins do not keep the cylinder in perfect square or coaxial alignment with the bore and breech face. Actually, modern revolvers seldom have perfect square with cylinder faces either.
The fault here is the threaded barrel hole and square barrel seat through the frame on solid frame guns and the arbor alignment or wedge fit on open frame guns.
 

denster

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M.D. said:
I don't even re-barrel my smokeless revolvers that close.
Dan Wesson revolvers are the only wheel guns I have ever seen set at .002 and they usually are set up for high velocity smokeless loads for silhouette use.
Smith and Wesson and Colt D/A revolvers are recommended set at .004-.006 with a minimum of .003 and max of .008. The Same standards apply to Ruger Single actions.


With a .002 cylinder gap many of the reproduction guns would rub on the six or twelve o'clock chamber as most arbors and base pins do not keep the cylinder in perfect square or coaxial alignment with the bore and breech face. Actually, modern revolvers seldom have perfect square with cylinder faces either.
The fault here is the threaded barrel hole and square barrel seat through the frame on solid frame guns and the arbor alignment or wedge fit on open frame guns.
You do realize of course, or maybe you don't, that when you cock one of the open tops there is no B/C gap because the hand pushes the cylinder forward against the rear of the barrel. Having a large B/C gap does several things none of them good. First it puts the cap further from the hammer when it falls lessening the impact and in extreme cases causing misfires. Then as the gun fires it allows considerable fouling to be deposited on the arbor which gets directed into the space between the arbor and cylinder causing binding after only a few shots. It also allows the cylinder to pick up speed as a projectile in recoil causing additional wear.
It is obvious from your writings that you have never tried it and are just making up reasons why it doesn't work. I would remind you that these are not modern cartridge revolvers and do not have a gas ring controlling the movement of the cylinder necessary to maintain headspace.
Generally your posts display a good general knowledge of guns but you missed the boat on this one.
 

M. De Land

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I respectfully disagree! I have never seen any black powder revolver original or reproduction purposely set up with a .002 cylinder gap from the factory or any where else.
Most all of them are on the generous side of .006 and virtually none of them are square with the breech face.
I do however believe that any thing over .008 is two much for any revolver percussion or otherwise.
 

hawkeye2

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"With a .002 cylinder gap many of the reproduction guns would rub on the six or twelve o'clock chamber as most arbors and base pins do not keep the cylinder in perfect square or coaxial alignment with the bore and breech face."

While that is true in many cases I have two open tops set up by Mike Brackett-Goons Gun Works which have .002" gaps with no problems so it can be done. .004" to .006" would be fine for the average revolver and isn't difficult to obtain on an open top. Remington styles require setting the barrel back a turn which involves taking material off the shoulder of the barrel where it meets the frame and then dressing the back of the barrel.
 

denster

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M.D. said:
I respectfully disagree! I have never seen any black powder revolver original or reproduction purposely set up with a .002 cylinder gap from the factory or any where else.
Most all of them are on the generous side of .006 and virtually none of them are square with the breech face.
I do however believe that any thing over .008 is two much for any revolver percussion or otherwise.
From the factory no it would be an added expense and Uberti can't even be persuaded to get the arbor length correct which is majorly why things can appear out of square. Pietta in the last few years has it pretty much down pat with the arbor and B/C gaps around .004 generally.
As to no one doing it goons gun works regularly sets them up to .0015 as a part of his tuning package.
With the open tops it's an easy job with The solid frames like Remingtons more trouble than it's worth.
Anyhow you do it your way and I'll do it mine.
 

hawkeye2

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"Having a large B/C gap does several things none of them good. First it puts the cap further from the hammer when it falls lessening the impact and in extreme cases causing misfires."

Good point. I can see the breast of the hammer hitting the frame in some cases before it had a chance to completely crush the cap which would be an extreme but not unheard of case. I have a well used (abused?) Euroarms Remington with a gap in excess of .010" and no ignition problems. It also has a very large 11 deg. forcing cone that I had to cut to remove the pitting there. It shoots fairly well considering all it's issues and fouling isn't any more of a problem than the average stock revolver.

"It also allows the cylinder to pick up speed as a projectile in recoil causing additional wear."


That's something I had never thought of. That would contribute to a brass frame shooting loose fast. I guess my steel Euroarms is destined to beat itself into oblivion but that's not something I'll bemoan. :grin:
 

M. De Land

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Well then I will give it a try as I have never seen or set up a percussion gun or any other revolver with that tight of a cylinder gap as I have always gone with manual specs.
Your reasoning makes sense to me Dennis and I love to try new ideas!
 

denster

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Actually the problem with cylinder movement is pretty well confined to the Colt open tops. The Remington design has the cylinder contacting the frame not the rear of the barrel. While you may have a large B/C gap on the Remington actual cylinder movement is generally minimal because that is determined by clearance between cylinder and frame. The bad thing is the Remington design is more sensitive to fouling on the base pin. My solution is shoot Alliant Black MZ in my Remington.
Good observation about the brassers and spot on. It would be interesting to see how long a tightly set up brasser would go.
 

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