Dragoon cylinder gap

[borne2fly]

Colt 3rd Dragoon (made around 1980) with over 0.010" cylinder gap, Also, that gap is dependent upon exactly where it is measured because the back of the barrel (cone?) face is way out of flat. This was right out of the box.

Had to grind off over 0.005" to clean this up. NOW it's flat.
Pushing the cylinder forward until it butts up to the cone, no light can be seen between the two. NOW they're parallel to each other.

Of course, all this only worsens the endshake. (Fix one problem, create another, etc ...)
So ... next step is to make a shim to fit between the frame and the back of the cylinder. My target is a 0.004" cylinder gap.
When re-attaching the barrel, I typically place a feeler gage between the cylinder and cone as the wedge is driven in (in this case it'll be a 0.004" feeler).
When a drag is felt on the feeler, and if I did all this right, the cone and cylinder should land parallel to each other as they are now.

 

[45D]

So, if you have to "set" the supposed "gap" by how far the wedge is driven in, then your just setting a temporary "endshake " setting. Your Dragoon doesn't have a bushing to establish a bonifid gap so in the instance of open top revolvers all you have is endshake ( the fore and aft movement of the cylinder).
It is in fact the length of the arbor that is the deciding factor as to how far the barrel assy will be pulled against the end of the arbor when the wedge is installed ( driven in sufficiently to maintain its position).
As you now know, your arbor isn't long enough to be that limiting factor and unfortunately you've added .005" more to the endshake you started with.

The limiting feature of the arbor has been a design element that has not been incorporated in any reproduction open top revolvers since the first reproductions were made ( yes, including the Colt 2nd and 3rd gens). Pietta is the only maker that has remedied this problem but it has only been the last dozen or so years. This known problem has long been called the "short arbor" or " short arbor syndrome" and can totally be corrected by installing a spacer in the arbor hole to take up space and give the arbor a surface to butt up to.

The end result is a repeatable reassembly of the open top revolver that will maintain a designated endshake ( my specs are .0025" - .003") and a sight picture that will also be maintained.

Mike

 

[borne2fly]

Mike, I'll do that eventually. Either a spacer or set screw tapped into the end of the arbor. So far the feeler seems to set the gap pretty consistently and the wedge appears to hold it all together quite well. I'm guessing the arbor will lose it's light press fit over time, and that's when I'll do what you've done.
And the deeper I go into this thing the rougher it gets .... looks like it was made with hacksaws and files I have a lot of deburring and polishing to do.

 

[borne2fly]

How is the nipple height set? Should the hammer close on the nipple with maybe 1 or 2 thou clearance? Or should it actually hit it? And how does this work with a little bit of endshake? I originally had to put shims under the nipples to get the hammer to fire the caps at all, and that doesn't sound right.

 

[45D]

Mike, I'll do that eventually. Either a spacer or set screw tapped into the end of the arbor. So far the feeler seems to set the gap pretty consistently and the wedge appears to hold it all together quite well. I'm guessing the arbor will lose it's light press fit over time, and that's when I'll do what you've done.
And the deeper I go into this thing the rougher it gets .... looks like it was made with hacksaws and files I have a lot of deburring and polishing to do.

A set screw isn't a good fix for the arbor length. Actually it would be best to make the revolver "solid" before "adjusting" for a permanent setup. You see, every time you shoot that Dragoon, the wedge is pinched and is given the ability to move. Driven in, the wedge will remain in place and a consistent setup will be maintained. Right now, it's a moving target and probably the cylinder would have locked if you drove the wedge all the way in. Take my advice and start at the beginning and build a solid open top rather than a patch job all along the way. Then you won't have to do the "nipple height " thing again.

Mike

 

[Stantheman86]

I have a Pietta Navy that was like that, I ran a file across the forcing cone until it "eyeballed" to a nice b/c gap, then I took it out and put 10 cylinders through it. Works great

If it not perfectly "even" I'm really not worried about it

 

[borne2fly]

A set screw isn't a good fix for the arbor length. Actually it would be best to make the revolver "solid" before "adjusting" for a permanent setup. You see, every time you shoot that Dragoon, the wedge is pinched and is given the ability to move. Driven in, the wedge will remain in place and a consistent setup will be maintained. Right now, it's a moving target and probably the cylinder would have locked if you drove the wedge all the way in. Take my advice and start at the beginning and build a solid open top rather than a patch job all along the way. Then you won't have to do the "nipple height " thing again.

Mike

So something like a 1/2” washer set into the arbor hole?

 

[borne2fly]

I have a Pietta Navy that was like that, I ran a file across the forcing cone until it "eyeballed" to a nice b/c gap, then I took it out and put 10 cylinders through it. Works great

If it not perfectly "even" I'm really not worried about it

I thought about doing that too, but this was a good excuse to dig out the tool post grinder. That thing’s been collecting dust for too many years.

 

[45D]

So something like a 1/2” washer set into the arbor hole?

Something more like this :

It's a #14 Pan Head sheet metal screw
with the shaft removed (#12 for belt pistols)

Sanded to an appropriate size:

Installed (round end in the bottom of the arbor hole).

Something like that.

Mike

 

[bang]

Yeah you should check and fix arbor first. A tapper in the gap is a sign. Hope when you fix the arbor it stays square.

 

[borne2fly]

Something more like this :
View attachment 177535

It's a #14 Pan Head sheet metal screw
with the shaft removed (#12 for belt pistols)
View attachment 177536

Sanded to an appropriate size:
View attachment 177538

Installed (round end in the bottom of the arbor hole).
View attachment 177541

Something like that.

Mike

I see. Got it. Looks like a good solid fix. Thanks!

 

[borne2fly]

I have a spare cylinder on the way and I’m told it probably won’t fit anything this old. Has anyone here tried swapping newer cylinders into pre-2000 guns?

 

[borne2fly]

Mike,
Pretty slick job on that skeletonized frame. I like it!

BTW, I took your advice on the arbor and made up a plug to drop into the arbor hole. I must admit, it's a lot more convenient than fiddling with the feeler gage.

-Don

 

[borne2fly]

I have a spare cylinder on the way and I’m told it probably won’t fit anything this old. Has anyone here tried swapping newer cylinders into pre-2000 guns?

Update ... spare cylinder arrived. Uberti. Plugged right into this 1980's Colt. Everything spins and locks as it should. Cylinder gap was different as expected ... I made a new shim to go behind the cylinder and now it's spot on.
So I'm getting the impression that certain parts CAN interchange with only minor work.

 

[M. De Land]

Colt 3rd Dragoon (made around 1980) with over 0.010" cylinder gap, Also, that gap is dependent upon exactly where it is measured because the back of the barrel (cone?) face is way out of flat. This was right out of the box.


View attachment 177473
View attachment 177475

Had to grind off over 0.005" to clean this up. NOW it's flat.
Pushing the cylinder forward until it butts up to the cone, no light can be seen between the two. NOW they're parallel to each other.

Of course, all this only worsens the endshake. (Fix one problem, create another, etc ...)
So ... next step is to make a shim to fit between the frame and the back of the cylinder. My target is a 0.004" cylinder gap.
When re-attaching the barrel, I typically place a feeler gage between the cylinder and cone as the wedge is driven in (in this case it'll be a 0.004" feeler).
When a drag is felt on the feeler, and if I did all this right, the cone and cylinder should land parallel to each other as they are now.

 

[M. De Land]

On the 60 I just rebuilt the gap total was .027 and the cylinder face was out of level. The face had to be dressed level to begin with. I had to build a new wedge and trim the lower lug so the key draw up on the arbor was parallel to the lug seat reduction.
I'm wondering if the washer shim at the cylinder base may require a hand stretch on your gun and if it will hold up to recoil. I've not made a gap reduction from the rear as you are doing so am very interested in how it works out. Thanks for sharing.

 

[borne2fly]

On the 60 I just rebuilt the gap total was .027 and the cylinder face was out of level. The face had to be dressed level to begin with. I had to build a new wedge and trim the lower lug so the key draw up on the arbor was parallel to the lug seat reduction.
I'm wondering if the washer shim at the cylinder base may require a hand stretch on your gun and if it will hold up to recoil. I've not made a gap reduction from the rear as you are doing so am very interested in how it works out. Thanks for sharing.

I haven’t fired it since the rework, but the shim is just a thin steel washer. I imagine it should be fine. My gap wasn’t as large as yours so I didn’t do anything that cut into the frame or barrel other than to lightly surface the cone face. With a gap of .027 I’d probably use a .022 shim behind the cylinder and check that everything spins and locks when it should. And most likely longer nipples would be needed, or alternatively shim washers under those too

 

[M. De Land]

I haven’t fired it since the rework, but the shim is just a thin steel washer. I imagine it should be fine. My gap wasn’t as large as yours so I didn’t do anything that cut into the frame or barrel other than to lightly surface the cone face. With a gap of .027 I’d probably use a .022 shim behind the cylinder and check that everything spins and locks when it should. And most likely longer nipples would be needed, or alternatively shim washers under those too

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!

 

[45D]

Update ... spare cylinder arrived. Uberti. Plugged right into this 1980's Colt. Everything spins and locks as it should. Cylinder gap was different as expected ... I made a new shim to go behind the cylinder and now it's spot on.
So I'm getting the impression that certain parts CAN interchange with only minor work.

The bearing surface is the "recoil ring" on a cap gun. A shim behind the ratchet isn't a good idea. Got a picture?

Mike

 

[45D]

Bump