Dragoon cylinder gap

[borne2fly]

Bump

Shim is 303 SS.
Drops onto the rear of the cylinder with 2-3 thou clearance, and does not interfere with the hand.
OD was a bit of a compromise ... I wanted the outer diameter to be at least as large as the ring on the frame, but this would have caught the hammer when it closed. So had to reduce it slightly to clear the hammer. As it stands, it sticks out into the cap pockets a bit but not quite enough to prevent access to the caps. Nipples are the longer ones from Track of the Wolf to make up the extra distance caused by the shim.

 

[borne2fly]

The motivation for all this was to be able to swap cylinders, where each cylinder's length can vary slightly. So I decided to leave the frame/barrel as-is, since it already seems to have enough space to accommodate the longest cylinder I have, and make up any differences using shims that partner with each particular cylinder.

I added the solid spacer in the arbor hole, and this took a few passes until I got the right spacer. My goal was to prevent any barrel "tip-up" or "tip-down", but to keep it coaxial with the cylinder. Meanwhile, I made this aluminum dummy cylinder for fun and noted that the cylinder butted up perfectly flat against the cone when pushed forward ... perfect.
Well, not quite .....

Note the witness marks on the front of the cylinder (from dry firing).
Ideally these should be perfectly round. The cone was ground true on a lathe, so this would seem to indicate a very slight left-right misalignment of the barrel WRT to cylinder.
Now, ... if I try measuring these "dents" I'm lucky to measure even one tenth. This is one of those things you can see in the right light, and almost feel with your fingers, but quite difficult to actually quantify.
So while this is sorta interesting I'm hard pressed to call it a problem that needs correction. Reckon I'll leave well enough alone and call it done .... before I REALLY screw something up

 

[borne2fly]

Off to the range ...

 

[borne2fly]

I'm curious if the shim stock steel ( which is annealed and soft) will resist the ratchet star imprinting and deforming it from recoil much as a brass frame does with heavy loads!

Good question. Mine has a steel frame, not brass. If I made brass shims instead, it might be possible to measure the "flattening out" of the shim after a few heavy loads, as an experiment.
I would rather see the shim wear out instead of the frame, and just periodically drop in a new shim.

I had considered oilite bronze since it is self lubricating. However, it's a sintered metal and I don't know how well it would hold up under the impact experienced here. One advantage might be the cushion it would provide, with the understanding that it would wear out frequently as a "sacrificial" component.

 

[M. De Land]

The motivation for all this was to be able to swap cylinders, where each cylinder's length can vary slightly. So I decided to leave the frame/barrel as-is, since it already seems to have enough space to accommodate the longest cylinder I have, and make up any differences using shims that partner with each particular cylinder.

I added the solid spacer in the arbor hole, and this took a few passes until I got the right spacer. My goal was to prevent any barrel "tip-up" or "tip-down", but to keep it coaxial with the cylinder. Meanwhile, I made this aluminum dummy cylinder for fun and noted that the cylinder butted up perfectly flat against the cone when pushed forward ... perfect.
Well, not quite .....

View attachment 179664View attachment 179665

Note the witness marks on the front of the cylinder (from dry firing).
Ideally these should be perfectly round. The cone was ground true on a lathe, so this would seem to indicate a very slight left-right misalignment of the barrel WRT to cylinder.
Now, ... if I try measuring these "dents" I'm lucky to measure even one tenth. This is one of those things you can see in the right light, and almost feel with your fingers, but quite difficult to actually quantify.
So while this is sorta interesting I'm hard pressed to call it a problem that needs correction. Reckon I'll leave well enough alone and call it done .... before I REALLY screw something up

It is very seldom if ever that one finds perfect barrel breech to cylinder face square, even in modern revolvers and with an arbor and well slip fit arrangement it is non existent as can quickly be determined with a feeler gauge. Frankly it has always been a pleasant surprise to me that revolvers have any accuracy at all given the opportunity of so many separate parts to be misaligned.
They do amazingly well any way though much to our delight ! I guess it's a system of Wibbles compensating for Wobbles !
Actually with open frame guns one can adjust them to shoot high or low some what by manipulating lower lug height and wedge depth without having to change front sight height. But no matter what with the tolerance required to make them slip fit into the arbor well there will never be the rigidness of a solid frame gun no matter how hard one jambs the arbor end into the well bottom.

 

[45D]

Actually with open frame guns one can adjust them to shoot high or low some what by manipulating lower lug height and wedge depth without having to change front sight height. But no matter what with the tolerance required to make them slip fit into the arbor well there will never be the rigidness of a solid frame gun no matter how hard one jambs the arbor end into the well bottom.

Actually, it's the other way around. The arbor length is what determines the end result of the barrel's "attitude". The barrel lug / frame joint is a constant and is foundational.

The open-top platform ( done right) allows me to shoot lower end "Ruger only" loads from one with absolutely no problems. The same loads I'm afraid actually caused movement in a Pietta top strap revolver (unmentionable) . . . it's all about understanding how it works and a close tolerance build . . .
Colt didn't build a revolver around a wedge, he built it around an arbor . . . literally . . .

Mike

 

[45D]

The motivation for all this was to be able to swap cylinders, where each cylinder's length can vary slightly. So I decided to leave the frame/barrel as-is, since it already seems to have enough space to accommodate the longest cylinder I have, and make up any differences using shims that partner with each particular cylinder.

Usually you fit the short cylinder to the frame and reduce the others accordingly (shouldn't be much unless they are "renegade" cylinders). That way you end up with one frame, several cylinders and no "extras".
This is why I like Uberti open-top revolvers and fitting Pietta length cylinders (unmentionables) to them. You get to the "spec" endshake quicker without any possible "added" barrel tilt.

Mike

 

[borne2fly]

Usually you fit the short cylinder to the frame and reduce the others accordingly (shouldn't be much unless they are "renegade" cylinders). That way you end up with one frame, several cylinders and no "extras".
This is why I like Uberti open-top revolvers and fitting Pietta length cylinders (unmentionables) to them. You get to the "spec" endshake quicker without any possible "added" barrel tilt.

Mike

I'm a bit reluctant to do that, at least not yet, because it would seem to require that I "shorten the gun" from where it is now. Either by shaving the barrel or frame where they meet at the bottom. I'm assuming that needs to be done with great precision.
And this is one of those 1980's serialized Colt things, and I was warned not to go chopping away at it (not altogether sure why, since it's not a real antique). Part of me agrees with that, but I've also seen so many things wrong with it right out of the box (and I'm not even a gunsmith), that unless I did something it was never going to be much more than an overpriced wall hanger.
Every part appears to be serialized, including the cylinder. That cylinder is neither the longest nor the shortest one I have that fits it, but it's the one that came with it. If I did modify the frame or barrel, it would be to get the right fit for that serialized cylinder. And I would still end up adding shims to fit the shorter cylinders.

 

[borne2fly]

Usually you fit the short cylinder to the frame and reduce the others accordingly (shouldn't be much unless they are "renegade" cylinders). That way you end up with one frame, several cylinders and no "extras".
This is why I like Uberti open-top revolvers and fitting Pietta length cylinders (unmentionables) to them. You get to the "spec" endshake quicker without any possible "added" barrel tilt.

Mike

>> "This is why I like Uberti open-top revolvers and fitting Pietta length cylinders (unmentionables) to them ...."

Ok, I was wondering if you could swap parts between Uberti and Pietta. Even if a little machine work was involved. Thanks!
-Don

 

[M. De Land]

Actually, it's the other way around. The arbor length is what determines the end result of the barrel's "attitude". The barrel lug / frame joint is a constant and is foundational.

The open-top platform ( done right) allows me to shoot lower end "Ruger only" loads from one with absolutely no problems. The same loads I'm afraid actually caused movement in a Pietta top strap revolver (unmentionable) . . . it's all about understanding how it works and a close tolerance build . . .
Colt didn't build a revolver around a wedge, he built it around an arbor . . . literally . . .

Mike

So I take it you have no experience with lug height alteration .

 

[M. De Land]

I'm a bit reluctant to do that, at least not yet, because it would seem to require that I "shorten the gun" from where it is now. Either by shaving the barrel or frame where they meet at the bottom. I'm assuming that needs to be done with great precision.
And this is one of those 1980's serialized Colt things, and I was warned not to go chopping away at it (not altogether sure why, since it's not a real antique). Part of me agrees with that, but I've also seen so many things wrong with it right out of the box (and I'm not even a gunsmith), that unless I did something it was never going to be much more than an overpriced wall hanger.
Every part appears to be serialized, including the cylinder. That cylinder is neither the longest nor the shortest one I have that fits it, but it's the one that came with it. If I did modify the frame or barrel, it would be to get the right fit for that serialized cylinder. And I would still end up adding shims to fit the shorter cylinders.

I like to read what Linebaugh, Bowen , Kuanhaussen and folks on this forum have to say about revolvers then add my own experience and determine whats the best approach for the project I'm working on. The truth is you will learn more about what works and what doesn't by experience of your own keeping in mind no one knows it all and we all have things to learn and try to see if it works for us.
We get into boxes when we figure there is only one way to do a job because some one else says so.

 

[45D]

So I take it you have no experience with lug height alteration .

The need to do that would be because of a short forcing cone (actually to mitigate a too short cylinder which leads to an exaggerated upward tilted barrel) . . . and that is rather rare. I've had to do that only a few times because of "Bubba". You definitely don't want "iight contact" there!!

The ability to lock up the cylinder with the wedge indicates the tolerances are "there" already, so there's really no reason to do anything at the barrel lug / frame junction. Correcting the arbor length is all that's needed to maintain acceptable barrel attitude along with close tolerances.

Mike

 

[M. De Land]

The need to do that would be because of a short forcing cone (actually to mitigate a too short cylinder which leads to an exaggerated upward tilted barrel) . . . and that is rather rare. I've had to do that only a few times because of "Bubba". You definitely don't want "iight contact" there!!

The ability to lock up the cylinder with the wedge indicates the tolerances are "there" already, so there's really no reason to do anything at the barrel lug / frame junction. Correcting the arbor length is all that's needed to maintain acceptable barrel attitude along with close tolerances.

Mike

I would not use that approach for closing large barrel cylinder gaps but I'm always interested in hearing another point of view even when I believe it's incorrect.

 

[45D]

I would not use that approach for closing large barrel cylinder gaps but I'm always interested in hearing another point of view even when I believe it's incorrect.

Ok, now I'm confused. If you wouldn't use that method for a larger than normal " set back" ( to keep from having an obvious barrel tilt) what would you ever use it for?

My point is, the revolver out of the box is pretty close as far as barrel location . . . definitely in the ballpark with the cylinder it came with. So much so that merely driving the wedge in too far can lock up the cylinder . . . So just fixing the arbor length so cyl lock up won't happen (and will give you a repeatable, accurate endshake ) there is no need to ever do anything to the barrel lug/ frame joint.

Mike

 

[45D]

As an aside, you may not like my methods but they are pretty much the same ideas described by Pettifogger and executed by thousands over the last almost 20 yrs.

Like you, I try to find the best way to execute a certain method or a better or more accurate way to achieve the same result. But I'm going for a known method that works.

My version of the arbor correction along with my additions and the setup I've developed over the last dozen years (and tested by hundreds and hundreds of customers) has allowed me to be able to shoot rounds that even I would have thought to be out of reach even a year ago. Low end Ruger only loads out of an Italian open top revolver is pretty impressive . . . thank you Larson Pettifogger for showing the way, thank you Jim Martin for teaching me how the Colt factory tuned their own product and could make it virtually indestructible, thank you Jerry Kuhnhausen/Jim Martin for the easy to understand Colt factory build manuals as well as factory repair / diagnostic manual! And of course, thanks to Walt Kirst for his most excellent product which was the vehicle that MADE me have to go down this open-top road!!!
Learning from those that "really" know reduces the time-line and allows exploring "newer/ even better ideas" .

Mike

 

[M. De Land]

Ok, now I'm confused. If you wouldn't use that method for a larger than normal " set back" ( to keep from having an obvious barrel tilt) what would you ever use it for?

My point is, the revolver out of the box is pretty close as far as barrel location . . . definitely in the ballpark with the cylinder it came with. So much so that merely driving the wedge in too far can lock up the cylinder . . . So just fixing the arbor length so cyl lock up won't happen (and will give you a repeatable, accurate endshake ) there is no need to ever do anything to the barrel lug/ frame joint.

Mike

Well since you ask, if the barrel/cylinder gap starts out reasonably square/level to the barrel breech from the factory but is excessive ( .027 in a 60 recently) than any move back of the barrel on the arbor (tightening the gap) by pushing the wedge deeper must be accompanied by an equal in lug reduction or we get pitch up or down by the cantilever effect of the lug. The wedge depth controls the gap tightening and the lug height controls the pitch up or down of bore to chamber attitude. Thus if we leave the lug long and draw up the gap with the wedge the muzzle will pitch upward and vice versa.
My main argument with this method of adjusting the vertical is it tends to bend the arbor once it exceeds the arbor and well clearance fit.
The challenge is to reduce the gap and maintain square as chamber-bore co-axis (alignment) will generally produce the best accuracy. This will often mean a new, taller front sight blade install as most open frame guns come from the factory shooting high and to one side or the other on bullseye targets at 25 yards.
Still if one does not want to replace the front sight than a pitch up can be introduced by leaving the lug long.

 

[borne2fly]

Well since you ask, if the barrel/cylinder gap starts out reasonably square/level to the barrel breech from the factory but is excessive ( .027 in a 60 recently) than any move back of the barrel on the arbor (tightening the gap) by pushing the wedge deeper must be accompanied by an equal in lug reduction or we get pitch up or down by the cantilever effect of the lug. The wedge depth controls the gap tightening and the lug height controls the pitch up or down of bore to chamber attitude. Thus if we leave the lug long and draw up the gap with the wedge the muzzle will pitch upward and vice versa.
My main argument with this method of adjusting the vertical is it tends to bend the arbor once it exceeds the arbor and well clearance fit.
The challenge is to reduce the gap and maintain square as chamber-bore co-axis (alignment) will generally produce the best accuracy. This will often mean a new, taller front sight blade install as most open frame guns come from the factory shooting high and to one side or the other on bullseye targets at 25 yards.
Still if one does not want to replace the front sight than a pitch up can be introduced by leaving the lug long.

>> "....but is excessive ( .027 in a 60 recently) ...).

One of my cylinders was this bad. I made a 0.020" spacer ring to go behind the cylinder.
No timing issues. Everything still spins and locks when it should. Barrel and the active cylinder aligned coaxially so there's no up or down tipping. I also use a precision spacer in front of the arbor to maintain a consistent re-assembly. Haven't done anything to the lug.
I'm a relative newbie at this cap & ball thing, so I could be way off base with all this. I'm just treating this like any other machine in the shop.
-Don