Trying to understand this “short arbor” on Uberti revolvers

[Lippy984]

Hi all,
So I recently bought a Uberti 1860 Army from Taylor’s. I stripped it down and cleaned and de-burred, which seemed not to be too bad at all. Maybe that’s why Taylor’s are good...anyways, always reading how Uberti Colts all have this short arbor problem, I checked with the cylinder removed and barrel at 90deg, it slides on .080-.100 past the frame. So that tells me the arbor is short. However, I have no issues installing and removing the wedge with little thumb pressure. And not measuring, with holding the cylinder back, it looks like I have somewhere between .005- .010” gap at the forcing cone. And I can see a sliver of light at the mounting lugs.
So my question is, what issues does one get with a short arbor?
The only issue I seem to have, is that I can run through 2 cylinders, but then need to clean the fouling otherwise it gets hard to rotate. But that could be normal, I’m new to revolvers.
By the way, I was using 25gr. Of Goex 3f, pre-lubed wad and a .454 round ball.

 

[Phil Coffins]

A short arbor causes an inconsistency of the cylinder location. That in turn means the barrel isn’t going to be in a predictable location so the best accuracy and dependable functionality is compromised.

 

[Musketeer]

Along with what Phil was saying, my understanding is that the arbor should bottom out in its hole in the barrel assembly, so that the barrel is always in the same position in relation to the cylinder and the wedge should be tight and need to be tapped in an out. This is in fact how the arbor is on my old Uberti Dragoon (not sure of its exact age, but I picked it up used in the late '90s). My much newer Uberti 1860 has the short arbor, which means the wedge is loose (able to be pushed in or out with very modest pressure) and the barrel position on the gun changes depending on how far you push the wedge in.

On my Dragoon the wedge must be tapped in with a non marring hammer, piece of wood, etc., and only serves to hold the barrel firmly onto the arbor. On the 1860 I could press it in with my thumb to the same position as on my Dragoon, but I could also push it in farther. As the wedge was pressed in farther, the forcing cone got closer to the face of the cylinder. When I pushed the wedge in far enough (or after I fired a shot or two from the gun and the wedge moved on its own) the front of the cylinder actually touched the forcing cone on the barrel. This both wore the bluing off the face of the cylinder and lead to binding issues as the gun got dirty.

I found a stainless steel washer of the appropriate diameter to just barely fit down into the arbor hole under the barrel (and a bit thicker than I needed) and then sanded it a bit at a time until it was of the proper thickness to both cause the arbor to bottom out against it and give me the proper barrel/cylinder gap, as well as a snug wedge.

edit: Sorry, had to do some edits. I just rolled out of the rack and I'm still a bit groggy. Hope this edited version makes more sense.

 

[bang]

Ditto on above. Making arbor bottom out makes the whole system like a solid mass.

 

[wb78963]

a very competent and experienced gunsmith recommended a #10 split (lock) washer for a short arbor correction.
My Uberti Dragoon was cured with a brass washer JB welded to the end of the arbor then filed to fit.
My Pietta revolvers do not have that problem.
That is my experience

 

[Lippy984]

So is it actually a tight fitting wedge we’re after? Or is that a correction to be made after the adjusted arbor length

 

[Musketeer]

Once you have the gap filled in between the end of the arbor and the bottom of the hole it fits into under the barrel and your barrel/cylinder gap is set, the wedge should fit tightly into the gun. You may need to do some additional fitting between the wedge and the slots is goes through in the barrel assembly or you may not. In my case I did not and the wedge fit nice and snug without being too tight. The wedge is too tight if you can't tap it with moderate force (you don't want to have to really hammer it, or at least I don't) far enough through for the little hook on the end of the wedge's retainer spring to protrude on the opposite side of the barrel assembly. If you can't do this, then you might need to do a tiny bit of filing/sanding on one side of the wedge until it fits.

edit: Just to be clear, I will add that if such an adjustment is necessary, I would ALWAYS suggest modifying the wedge and not the barrel slots, as wedges are relatively cheap and replaceable.

 

[Lippy984]

Once you have the gap filled in between the end of the arbor and the bottom of the hole it fits into under the barrel and your barrel/cylinder gap is set, the wedge should fit tightly into the gun. You may need to do some additional fitting between the wedge and the slots is goes through in the barrel assembly or you may not. In my case I did not and the wedge fit nice and snug without being too tight. The wedge is too tight if you can't tap it with moderate force (you don't want to have to really hammer it, or at least I don't) far enough through for the little hook on the end of the wedge's retainer spring to protrude on the opposite side of the barrel assembly. If you can't do this, then you might need to do a tiny bit of filing/sanding on one side of the wedge until it fits.

Okay, got that. ...so what is the target barrel/cylinder gap I’m looking to achieve? And do I check this at rest? Full cock with pushing the cylinder back?

 

[Phil Coffins]

What you’re after is a correct fit on the arbor that results in a barrel cylinder gap that is consistent and the wedge going in firmly to the right depth. To have it right is all these things happening at the same time. The pistol came to you ready to shoot but with the least amount of fitting at the factory. That allows them to sell us a replica at the lowest price possible. Many of us want as good as pistol as our pocket book and or knowledge allows. Skill level dictates how we get there. We all buy these and many of us realize that they are more like assembled kits then accurate copy’s of originals. A fun hobby to be sure.

 

[Musketeer]

I set mine to .008" (some may prefer a different amount) with the wedge installed and the hammer down. The cylinder will move forward a tiny amount when the gun is cocked and then move back after the shot is fired, but I found the .008" gap in the "resting" position made the gun work just fine and didn't allow the gap to close while cocked to a point where it actually touched the forcing cone.

Edit: Actually, I lied. I just went and measured it and the resting gap is .010". It's been a while since I made this mod, and I'm not sure why the .008" figure popped into my mind when recalling this, but it did. Just for giggles I checked the gap with the hammer cocked and it would just barely let a .006 feeler through. This is a bit larger than most like, but it works for me and makes fowling a non issue.

 

[Lippy984]

What you’re after is a correct fit on the arbor that results in a barrel cylinder gap that is consistent and the wedge going in firmly to the right depth. To have it right is all these things happening at the same time. The pistol came to you ready to shoot but with the least amount of fitting at the factory. That allows them to sell us a replica at the lowest price possible. Many of us want as good as pistol as our pocket book and or knowledge allows. Skill level dictates how we get there. We all buy these and many of us realize that they are more like assembled kits then accurate copy’s of originals. A fun hobby to be sure.

Well that’s exactly what I like about this stuff. It make you think

 

[Lippy984]

I set mine to .008" (some may prefer a different amount) with the wedge installed and the hammer down. The cylinder will move forward a tiny amount when the gun is cocked and then move back after the shot is fired, but I found the .008" gap in the "resting" position made the gun work just fine and didn't allow the gap to close while cocked to a point where it actually touched the forcing cone.

Edit: Actually, I lied. I just went and measured it and the resting gap is .010". It's been a while since I made this mod, and I'm not sure why the .008" figure popped into my mind when recalling this, but it did. Just for giggles I checked the gap with the hammer cocked and it would just barely let a .006 feeler through. This is a bit larger than most like, but it works for me and makes fowling a non issue.

Good to know...so .008-.010, hammer down, as it lies

 

[Musketeer]

Yeah. Many people like a smaller gap, even down to .002 or so, in the cocked position. Obviously a smaller gap will give you less gas loss and higher velocity, but these are just fun guns for me (plinking mostly), so I'm not really concerned with that. I mainly was tired of the front of the cylinder scraping against the forcing cone and the gun binding up after a small number of shots. As it is now I can spend an afternoon out plinking in the desert without cleaning or fiddling and have no troubles.

 

[Lippy984]

Yeah. Many people like a smaller gap, even down to .002 or so, in the cocked position. Obviously a smaller gap will give you less gas loss and higher velocity, but these are just fun guns for me (plinking mostly), so I'm not really concerned with that. I mainly was tired of the front of the cylinder scraping against the forcing cone and the gun binding up after a small number of shots. As it is now I can spend an afternoon out plinking in the desert without cleaning or fiddling and have no troubles.

Wow that would be wonderful...I’m going to measure it first. Fouling seemed a bit excessive, but then again I’m new to revolvers.

 

[Lippy984]

Thank you all for the help

 

[Stantheman86]

Colt originally fitted the revolvers to have a correctly fitted Arbor to Arbor Hole fit. That was pretty much the key to making these revolvers strong enough to stand up to heavy use. The Arbor would correctly fit and the wedge slot would line up.

It likely saves Production Man Hours to just quickly bore the Arbor Hole and assemble the guns, knowing 95% of end users will fire a handful of shots and put the piece on a mantle etc.

I didn't know about all this when I owned Piettas but now I'm intrigued.

That said, the last Pietta I owned in 2011 or so , peened the wedge slot when I fired conicals with Pyrodex. So I'd probably feel better using brass washers to shim up my Ubertis

 

[wb78963]

since I shoot a lot with snub nose 1851 .44 Navy Pietta fantasy guns loading off the frame is necessary.
I have perfectly good accuracy and reliability with a properly fitted wedge pushed in just thumb tight. After 5 or 6 rounds the wedge needs a gentle tap to be removed.
This is after shooting many hundreds of rounds through several snub nose revolvers. I do not pound the wedge in with a hammer, but it seems to me the more I shoot the tighter the wedge gets.
But a man ought to do what he thinks best, so hammer away, and pinch those caps. It is your gun
Bunk

 

[Stantheman86]

Good tip on using the #10 brass washers

 

[Gun Tramp]

Colt originally fitted the revolvers to have a correctly fitted Arbor to Arbor Hole fit. That was pretty much the key to making these revolvers strong enough to stand up to heavy use. The Arbor would correctly fit and the wedge slot would line up.

Stan, could you cite your source for this information? I'm looking for "factory assembly and ordnance rebuild specifications" for the open-tops, similar to what I've found for later Colt's. I don't buy the "short arbor" theory and still wish someone would explain why wedges on originals were so carefully fitted that they were serial numbered to the gun.

 

[wb78963]

because each one of those guns were put together by a grey headed GUNSMITH with green eye shade and a years of experience not a man with a box of parts and an air driven wrench.
The wedges on my guns are fitted by a man like that. They go in thumb tight and always close up the same way.