Just curious about what the gap should be. My Uberti 1862 pocket police is at around 8 to 9 thousandths. That’s with the arbor properly shimmed to length because of course it was too short! And that is measured with hammer down on a fully assembled revolver.
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Appropriate cylinder gap for Colt revolvers
- Thread starter 1stnamebassist
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Snooterpup
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Sounds like it may be a bit over shimmed. I'm not real happy with anything over .004. Just my opinion. I think the gap should be measured with the gun assembled and at half-cock
with the cylinder pulled back to the recoil shield, not with the hammer down. Perhaps 45D will chime in. He does know what he's talking about.
with the cylinder pulled back to the recoil shield, not with the hammer down. Perhaps 45D will chime in. He does know what he's talking about.
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The hammer can be down as long as you push down the cylinder to the recoil shield depressing the hand spring which is no great feat. Also a feeler gauge is used by "feel" not what can be jammed between to surfaces.
Keep in mind closing the barrel cylinder gap (end shake is a term properly used for the space between the bearing spud and the frame in cylinders with bearing spuds in the front ) is correctly achieved by moving it forward square to the barrel breech which is impossible if one does not also adjust the lug contact height along with wedge depth. On occasion if a great amount of gap must be closed the barrel slots forward will also need extending.
End fit of the arbor is a good thing for consistent wedge depth gauging but not critical to accuacy or longevity and has no strengthening effect to the arbor end. If the end of the arbor is going to separate it will wither making contact or not because the butt joint remains. The arbor and arbor well never become one unit no matter how hard you jamb the ends together because of the butt joint.
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Ok I checked it at halfcock with cylinder pushed back and I measured .015. I drove the wedge in a bit more and got around .013. Now the question becomes how do I tighten it up a bit and is it really necessary? I haven’t shot it yet and just installed an action shield and decided to check the gap and I thought it was a bit high.
My education is deficient in various ways but I appreciate learning all the nomenclature possible.
What is a bearing spud?
Is a butt joint the contact between the arbor slot and the wedge?
“Barrel slots forward”?
Forever I have checked end-shake by placing on half cock, muzzle elevated and pressing down on the cylinder. That’s how, right? If the hammer is down may not the bolt potentially effect the measurement?
What is a bearing spud?
Is a butt joint the contact between the arbor slot and the wedge?
“Barrel slots forward”?
Forever I have checked end-shake by placing on half cock, muzzle elevated and pressing down on the cylinder. That’s how, right? If the hammer is down may not the bolt potentially effect the measurement?
I think you may need to reduce the shim or shims to get to your number which should be right at .003".
I set customers up with .0025" - .003".
"Properly" shimed may be a "broad" term. Nothing starts counting until the barrel lug contacts the frame . . . then you start closing in on your target number.
Mike
I’m with you. I’m new to black powder and the terminology is above me for the most part, but once I understand the concept I can generally fix the problem. I started working with metal with my dad when I was five, deburring parts while watching Gilligans Island and other shows of that time period! Worked in machine shops for half my working life and the other half as a Land Surveyor. I don’t have machinery at home, but with files and stones and a drill press and Dremel I can make most things I need.
Also by shims im talking about the end of the arbor bottoming out in the arbor hole under the barrel.
Well, you want them "more than touching", that's why I said that is you starting point. Now is when you start zeroing in your number.
Mostly just files and stones! And a drill press! So when I get the arbor touching the back of the arbor hole the wedge won’t go in. Also when you say start zeroing your number how is that done? Are you shimming behind the cylinder? I’m not sure if I’m understanding the process at this point. I would imagine that shimming more than a couple thousandths you would probably encounter problems with the hand functioning properly. Thanks kindly for the help! I did install an action shield the other day and it worked great. I copied it from photos I saw of the ones you installed! May do a cap post soon also. Not sure if it will be a necessity at this point. I don’t compete, but I still want the gun to function properly!
Gee Dog, I believe he's talking about the cylinder bushing head ( Colt parlance). The endshake is how much too short that bushing head is from the frame. That measurement is the difference in the cylinder gap taken with cylinder pushed forward and pushed back. The difference is the amount of endshake.
Butt joint is between barrel lug and frame. Means it's not locked together, they just "butt up" against each other. That's why the meeting of the two assemblies right there is the starting point for barrel/cylinder clearance.
"Barrel slots forward" - no clue.
Being that the barrel/cylinder "gap" is a defined opening and "endshake" is the amount of fore and aft movement of the cylinder, the open-top cap guns don't have a bushing to hold the cylinder face a specified distance from the f.c., therefore they have no "proper" gap. Because of that, the only measurement you can get is the maximum with the cylinder pulled to the rear. Pushed forward will equal 0. So, endshake is all one has in a cap gun. It is the amount of clearance the cylinder can move fore and aft.
BTW, Arbor correction is essential if you want a reproduction that is mechanically faithful to the original.
Mike
PM sent.
Just so you know, the arbor is short on the front end not the back end. The back is screwed into the frame. The spacer goes in the arbor hole so the arbor will contact it when inserted.
Mike
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Yeah that’s what I’ve been doing. I used a split washer that was too large and filed it down then put a dab of jb weld on the front of the arbor to hold the washer on. It was still a hair too short so I put a dab of jb weld on again and let it dry and flat filed it until the butt joint fit was perfect, then the wedge was a no go. I took a couple thousandths off the jb weld again so I could get the wedge in and the space between forcing cone and cylinder when pushed all the way back was I believe it was .013-.014. Fun stuff! I love these challenges!
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Yes bushing is the correct term used in the manuals but I like and use more descriptive terms to get my meanings across plus I didn't recall the technical term at the time I posted.
End shake clearance for the spud/bushing is a separate and distinct tolerance from barrel gap setting in cylinders that use them although the former figures into the latter. Typically end shake of the spud will be around .001 and barrel gaps are never less than .002 (Dan Wesson revolvers) and most come from the factory now days at about .004 -.006.
One does not want to big of a barrel gap in open frame guns as the hammer pushes the cylinder forward and at detonation the cylinder slams back against the recoil shield. The more run the cylinder has at the recoil shield because of a large gap the faster the gun loosens up.
Black powder is far less stressful to this because of its lower pressure.
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There is a sequence of steps to follow in setting up the pistol. Number one is setting up the arbor so it bottoms in the barrel.
Check the end shake, which should be about .003".
If it's too large, then shorten the arbor.
All of this is done with the barrel NOT contacting the frame lug.
With the barrel mounted to the arbor (off to the side of the frame lug) rotate it up to the frame. It should just mate up. If they don't and one needs to be shortened, I've carefully removed material from the frame lug. The locating pins need to come out to do this.
If the end shake is excessive, the cylinder will be pounded backwards causing wear, pressure will be lost, and flames will exit the gap (they will anyway), possibly causing a chain fire.
Anyway, it's just those three things - get the arbor length correct that gives minimal head shake, then line up the barrel and frame lugs.
Some guys even set them up with .001" gap, but you can run into problems going too tight.
Check the end shake, which should be about .003".
If it's too large, then shorten the arbor.
All of this is done with the barrel NOT contacting the frame lug.
With the barrel mounted to the arbor (off to the side of the frame lug) rotate it up to the frame. It should just mate up. If they don't and one needs to be shortened, I've carefully removed material from the frame lug. The locating pins need to come out to do this.
If the end shake is excessive, the cylinder will be pounded backwards causing wear, pressure will be lost, and flames will exit the gap (they will anyway), possibly causing a chain fire.
Anyway, it's just those three things - get the arbor length correct that gives minimal head shake, then line up the barrel and frame lugs.
Some guys even set them up with .001" gap, but you can run into problems going too tight.
