44-40 revolvers, unequal cylinder & bore diameters


Tall Pine
October 28, 2006, 04:25 PM
Would this cause the accuracy of the revolver to suffer, or cause other problems?

I have read this happens when a manuf sometimes slaps a cylinder in a 44-40 from their 44 mag or 44 spec stock to save costs. I am trying to decide between 44-40 and 45LC Cimarron model 1873 and this would impact the decision.


***EDIT---a local CAS gunshop owner just told me that the Ruger Vaquero was the only model he knew of that had this mismatch problem. Note-Ruger Vaquero no longer comes in 44-40***

If you enjoyed reading about "44-40 revolvers, unequal cylinder & bore diameters" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!
Wil Terry
October 28, 2006, 05:15 PM
If the cylinder throats are smaller than the barrel groove diameter you're outta luck until you open them up.
If the cylinder throats are larger than the barrel diameter you use bullets of throat diameter and a nice smooth forcing cone--it ain't called a forcing cone for nothing--will take care of all the rest and probably shoot pretty darned good.
Personally, I am amazed at how well all my 44-40 sixguns shoot. I have two convertible 44spl/44-40 sixguns, one a COLT and the other a S&W and in both cases the 44-40 cylinders are noticably more accurate than the 44SPL cylinders.
My 7 1/2" CIMARRON single action 44-40 shoots like a fine target pistol dead upon the sights at 25 yards.
All of my other 44-40 sixguns also shoot up a storm too. There ain't no flies on the old 44WCF/44-40 in a good sixgun.

Tall Pine
October 28, 2006, 06:35 PM
Thank you Wil.

Since Im buying a Cimarron, can you confirm for me that your Cimarron 7 1/2" is stock as far as the barrel & cylinder goes? (i.e. it did not have this mis-match problem)

When did you buy your Cimarron?

Wil Terry
October 28, 2006, 08:56 PM
It came directly from CIMARRON when they were still in Houston TX...around '92 maybe.

October 29, 2006, 01:34 AM
Simple answer.
Cimarron is aware of bore and cylinder mistolerance in .45 Colt and .44/40 revolvers of old.

If you go to Cimmarons website they have a chart of standard bore and cylinder tolerance dimensions that they require the manufacturer to hold.

It is not an issue you will need worry about if you buy a revolver from this company.


Tall Pine
October 29, 2006, 09:53 AM
Thank you Wil and Onmilo:

I looked at the Cimarron website and could only find the Bore-Groove-Twist chart (see below). Unless I dont understand it, I dont see anything mentioning the cylinder diameter specs matching the barrel bore. Please correct me or send me in the right direction.


October 29, 2006, 12:06 PM
With a nominal bore diameter of .4215" and a groove diameter of .429", a maximum chamber tolerence of .430" will allow acceptable accuracy without shaving lead.
Cimarron revolvers will meet these tolerence levels or they will rebarrel or replace the firearm.

The issues you are worrying about involved revolvers that used barrels bored to the early .427" groove diameter in .44 and chambers that were tolerenced at .430" or larger.
The problems were the same in .45 Colt guns that used .452" groove diameter barrels and chamber throats that measured .454" to .456"

October 31, 2006, 09:12 AM
The obnly 44-40 revolver I own is a Colt New Service. It's very accurate with 245 gr. LSWC except it shoots about 2 inches to the left at 50 ft.

Father Knows Best
October 31, 2006, 09:38 AM
Some of the terminology here is confusing to me, so let me try to just set forth my understanding of the issues with 44-40 revolvers. FWIW, I've been shooting single action 44-40's for years, and have spent years working them out, so I think I have a pretty good handle on things.

Originally, the standard bore major diameter (in the grooves) for 44-40 was .426, give or take. 19th and early 20th century 44-40 firearms are typically found with bore major diameters of .425 to .427. As a result, commercial 44-40 ammo is generally loaded with bullets sized to .426 or .427.

Around the same time that Winchester introduced the 44-40 (originally known as the .44 Winchester Central Fire, or .44WCF), Smith & Wesson developed a cartridge for the Russian government. It was the .44 S&W American cartridge, but with an inside-lubed bullet instead of the heeled bullet used in the .44 American. It became known as the .44 Russian. The .44 Russian used a bore major diameter of .429, and nominal lead bullet size was .430 to .431.

The .44 Russian was later lengthened to create the .44 S&W Special. The .44 Special was lengthened yet again in the 1950s to create the .44 Remington Magnum. The .44 Russian, Special and Magnum all use .429 bores and, therefore, .430 lead bullets.

At some point in time, various manufacturers responded to a perceived demand for "dual cylinder" revolvers chambered in both .44 Special or Magnum, and .44-40. Since the bore sizes were slightly different, however, they had to use the larger Russian/Special/Magnum bore, rather than the smaller 44-40 bore. Colt offered dual cylinder 44-40/44 Specials for years, for instance, and the dual cylinder models all had .429 barrels, while dedicated 44-40 revolvers wore .426 barrels.

It didn't hurt anything to shoot undersize 44-40 bullets down the larger barrels, though they might not have had the best accuracy and leading was theoretically more of a concern. If you had tried to force jacketed .430 magnum bullets down a .426 bore, however, bad things might have happened. Thus, the larger bores had to be used on the dual cylinder guns.

Later, some manufacturers apparently standardized on .429 barrels for all of their ".44" firearms, regardless of whether they were 44-40 or one of the Russian/Special/Magnum guns. Uberti, for example, appears to have been using .429 barrels exclusively on 44-40 firearms for many years. I've slugged any number of Uberti-made revolvers and rifles chambered in 44-40, and all had bore major diameters of .4295 +/- .0005. The reason for the standardization is almost certainly reduction in inventory and manufacturing cost.

Today, you really should slug any 44-40 firearm to verify the bore dimensions if you want to ensure best accuracy. It could range from .425 to .430, depending on who made it and when, and how tight their tolerances were. Most Colts and USFA's (other than dual cylinder models) will run .426, and most Ubertis and Rugers will go .429, but I've seen exceptions here and there.

The other important dimensions are the throats, and the chamber necks. For best accuracy in a revolver, throats should be .001 to .002 above bore major diameter. Thus, for a .429 bore, throats should be .430 to .431. Anything larger and the bullet may cock prior to entering the forcing cone. Anything smaller and the bullet will be swaged down to smaller than bore diameter before entering the cone. Both are bad for accuracy and can result in excessive leading. Ruger for some time had badly undersized throats on a lot of its .45 Colt revolvers, for instance. I've generally found Uberti and USFA 44-40 throats to be correct, however. All of my 44-40 Uberti revolvers with .429 barrels have correctly sized .4305 +/- .0005 throats.

Finally, you have the chamber necks. The chamber neck size determines the maximum cartridge diameter at the neck. If it is too small, you won't be able to get a cartridge with a large bullet to seat fully in the chamber. This is where I've come across the most problems. SAAMI spec for 44-40 chambers is .4435 at the case mouth. That spec is based on the original cartridge dimensions, however, which in turn used a .426 - .427 bullet for the standard .426 bore. The problem is that modern brass tends to run about .007 thick, and loading it with a .429 or .430 bullet can result in a cartridge that is too big at the neck to fit in a SAAMI spec chamber. For example, say you have a revolver with a .429 bore, .430 throats and SAAMI spec .4435 chamber neck. If you load a .430 bullet into brass that is .007 thick, you get a cartridge that measures .444 at the mouth, and that .444 cartridge is not going to fully seat in a chamber that is only .4435 at the neck. When you add in tolerance stacking issues, you may find that you can't reliably get any bullet larger than .427 or .428 to work, because anything larger results in cartridges that won't chamber.

At that point, you have a choice. You either live with shooting bullets that are smaller than your bore size (bad for accuracy and promotes leading), or you have the chambers opened up slightly at the necks to accommodate the larger bullets. The latter approach is the one I use. I had a customer chamber reamer made by Manson Precision that opens just the neck area of 44-40 revolver chambers by an additional .002, giving me enough space to reliably seat cartridges loaded with .430 lead bullets. My 44-40 revolvers now work great, with excellent accuracy and no leading at standard velocities.

If you enjoyed reading about "44-40 revolvers, unequal cylinder & bore diameters" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!