Barrel to Arbor Dimensions

[gunboat57]

I'm doing some research on Colt's conversion and open top cartridge revolvers.

Can someone with an original 1860 Army percussion revolver or an original Richards I or II cartridge revolver measure the centerline to centerline distance from the arbor to the barrel?

Can someone measure the arbor to barrel centerline to centerline distance on a modern Uberti 1860 Army percussion revolver?

If this information is already compiled somewhere, I'd appreciate a link.

Thanks in advance for any help!

[gunboat57]

Here's how I find the barrel to arbor center to center distance.  Measure inside top of barrel to inside bottom of arbor hole.  Then measure inside bottom of barrel to inside top of arbor hole.  Add the two measurements together and divide by two.

My Uberti OT shown comes out to .526".

[Coffinmaker]

  Gunboat 

I am actually of no help.  I don't own an original of any of your subjects nor do I own a sample example of a current Uberti 1860 Army.  However:

WHY??

[gunboat57]

"Why?"
OK, fair question.  I have two reasons for asking.

I have an Armi San Paolo "Navy" 44 Sheriff's model.  Not sure when it was made.  But I'm measuring a full .020" difference between the axes of the chambers and the barrel axis!  I'd like to confirm that in modern C & B revolvers like an Uberti the chambers and barrel are closer to being coaxial.

Second reason is more out of curiosity and a quest for useless knowledge.  On the original Richards I conversions some revolvers used the original rebated cylinders which were bored out for the .44 cartridge.  I'd like to know how thin the metal was over the chambers in the rebated portion of the cylinder.  I know the chamber diameters and I know the diameter of the rebated part of the cylinder.  I still need to know the center to center distance from the arbor to the chambers.  Next best thing would be C to C distance of arbor to barrel axis on an original Richards or original 1860 Army.

I know that Colt began making new rebated cylinders for the conversion revolvers and those cylinders were a bit larger in diameter.  And the Open Top revolvers did away with the rebated part altogether.

[dangt]

This would be best measured on the cylinder itself.  The dimension you want would be half the distance between two opposing chambers.  I am assuming the chambers are not diverging and are parallel to bore axis. Last comment was in regard to the quest for how thin over chambers at the breech.

[Coffinmaker]

  Gunboat

I wouldn't go so far as to call it "useless" information.  Well, not completely anyway.  Knowing the  center to center axis of the Barrel Bore and the Arbor Bore might enable one to determine if a modern reproduction barrel assembly can be fit to an original Colt.  Which, depending on the condition of the barrel assemble found on a "found" original, might just be an option.

As far as the two objects being coaxial, your methodology is a mite flawed.  Whether or not barrel and chamber are "coaxial" is determined with an appropriate sized "range rod."  Although, it will require a somewhat specialized range rod as, as oft happenstance, the chamber bore is "other" than the barrel bore.  Go figure.  So, one needs a range rod the actual dimension of the "lands" but perhaps stepped down the last quarter inch to match the chamber, then said rod should enter the chambers without hiccups.  Mostly.

Now, provided you have an appropriate forcing cone at the barrel breach, even a slight miss-alignment is corrected by the forcing cone.  Usually.

Back to mostly useless trivia.  None of these measurements will actually answer most questions.  Modern replicants of Conversions, submitted by Uberti, the cylinders are actually larger than the original sample examples, because Uberti bowed to the clamoring masses whom wanted conversions chambered in 45 Colt.  The actual amount of meat at the breach end of period conversions is best measured from an "actual."  Same same determining the dimension at the breach of a modern replicant.

One you have those actual dimensions, you will proudly own a winning, or several winning, answers for Trivial Pursuit     Burma Shave

PS:  The remaining thickness of steel in a modern replicant, chambered .45 Colt, does not count as useful trivia.  Colt never chambered ANY conversion in .45   Colt conversions on the 1860 platform were chambered for .44 Colt, which was actually a heal based bullet that fit the 1860 mostly .45 bore.  Go Figure.

[gunboat57]

DangT, you're right.  Most useful measurement off of an original Richards conversion or 1860 percussion revolver would be chamber to opposite chamber.
But you brought up something I was wondering.  Did Colt have to bore the chambers slightly convergent front to rear when reworking a percussion cylinder?  The bottoms of the bolt notches had to have been paper thin or even cut away sometimes.

 

[gunboat57]

Coffinmaker, just for fun I checked my Uberti 44 Special Open Top for "coaxiality" between barrel axis and chamber axes.  I used the arbor for my datum and was careful to measure on the lands in the barrel bore.

Happy to report that all axes were parallel and within a couple thousandths of being coaxial.  Must say I'm impressed with the quality of this revolver.

[U.S.M.R.]

Regarding the bolt cuts Adler's book shows a Richard's with no bottoms to the cuts.

[Coffinmaker]

  OK guys

The Open Top is and has been my favorite Colt Pattern Revolver.  I spent 20 years working on them and mostly other Open Top pattern guns.  My Open Tops have been favorite main match guns.  HOWEVER:  I have NEVER been happy with nor recommended the Open Top to be chambered in .45 Colt.  The chambers are just too thin.  I had countless customers who brought me guns, where the gun had spit the less than paper thin bottom of the notches out of the gun.  They continue to function just fine, it is just a bit disconcerting to see "Brass" at the bottom of the notch.

With regard to originals, they also were known to spit the bottom sliver out of the bottom of the notches because of the diameter of the.44 Colt cartridge.  Same, same, they continue to function just fine.

I also had the privilege of working on quite a few Original Open Tops.  I can confirm Colt DID NOT bore the chambers convergent.  Colt also DID NOT bore the chambers of their factory conversions of the 1860 revolvers with convergent chambers.  The ONLY chambers I have ever seen with convergent chambers were the older R&D two piece cylinders built with SIX chambers to accommodate the .45 Colt cartridge.

Additionally, Uberti actually got it right with one glaring flaw.  The Open Top is a TRUE Chameleon.  I st up my own Open Tops with ALL the available cartridge Cylinder/Barrel combination.  The guns are well enough made, they only required minor fitting.  The glaring error is the abysmal Barrel to Arbor fit, which Uberti has NEVER corrected.  And THAT is really a SHAME.

[gunboat57]

Seeing brass through the cylinder notches would kinda freak me out.

But hey, I checked the arbor fit on my Open Top 44 Special when the barrel lug is turned out of alignment with the frame.  I lucked out because the arbor bottoms out solidly when the barrel lug exactly lines up with the end of the frame.
This is the Open Top we talked about in another post with the chambers too short for 44 Special that I'm shooting with 44 Russian. Can't win 'em all!