The Colt Peacemaker barrel length conundrum

The Colt Peacemaker barrel length conundrum

When is a 7-1/2 inch barrel not a 7-1/2 inch barrel?

By Dennis Adler

The new Umarex Colt Peacemaker has a 7-1/2 inch barrel making it an authentic copy of the original Single Action Army models. The frame design, however, if from the late “Smokeless Powder Version” with the transverse cylinder latch c. 1892. The gun comes with wood grained plastic grips, but white grips are also available.

The new Umarex Colt Peacemaker has a 7-1/2 inch barrel making it an authentic copy of the original Single Action Army models. The frame design, however, is from the late “Smokeless Powder Version” with the transverse cylinder latch c. 1892. The gun comes with wood grained plastic grips, but white grips are also available.

This is a story about barrel lengths, overall lengths, conceptions, misconceptions, and interpretations, it’s also a story about how one gun can have two barrel lengths at the same time!

Let’s begin at the beginning, when Samuel Colt patented the revolver in 1835 (his first patent filed in Great Britain in October of that year) and again in February 1836 for his U.S. patent. (Colt knew that if a patent were filed first in the United States the same could not be applied for in Great Britain or France, whereas a U.S. patent could be granted regardless of whether there were foreign patents preceding it. He was pretty savvy for a young man).

The first Colt Paterson revolvers produced from 1835 to around 1842 had barrels that were nearly flush against the front of the cylinder, and held to the lower frame by a wedge passing through the barrel lug and cylinder arbor.

The first Colt Paterson revolvers produced from 1835 to around 1842 had barrels that were nearly flush against the front of the cylinder, and held to the lower frame by a wedge passing through the barrel lug and cylinder arbor.

Colt measured his barrel lengths by, well, simply measuring the barrel from one end to the other. His first handguns were open top designs, thus the barrel length was pretty clear. The back of the barrel was nearly flush with the front of the cylinder. A wedge passing through a slot in the barrel lug corresponded with a slot in the cylinder arbor, with the wedge passing all the way through to the other side of the lug and securing the barrel to the frame.

In this close-up of a Colt Paterson you can see how the barrel almost touches the front of the top cylinder chamber. The wedge, held in place by a screw, passes completely through the barrel lug and the cylinder arbor. This was the only means by which the barrel was secured to the lower frame.

In this close-up of a Colt Paterson you can see how the barrel almost touches the front of the top cylinder chamber. The wedge, held in place by a screw, passes completely through the barrel lug and the cylinder arbor. This was the only means by which the barrel was secured to the lower frame.

In 1847 Colt introduced the .44 caliber Walker pistol, and with it a change to the back of the barrel lug which was no longer flush to the face of the cylinder, but rather cleared the cylinder by an average of 3/16th of an inch. A forcing cone was added at the back of the barrel to close the gap between the barrel breech and the top cylinder chamber. This has remained the standard barrel to cylinder design to the present day.

After 1847, Colt began using a barrel lug that aligned with the front of the lower frame and left a short gap between the back of the lug and the cylinder. This was to help facilitate loading the revolver. The distance from the back of the barrel lug to the top cylinder chamber was bridged by a forcing cone that was nearly flush to the cylinder, as shown on a Colt 1851 Navy (bottom). In 1858 E. Remington & Sons introduced their Navy and Army models revolvers (top) which used a solid topstrap frame with the barrel threaded into the frame.

After 1847, Colt used a barrel lug that aligned with the front of the lower frame, leaving a short gap between the back of the lug and the cylinder. This was to help facilitate loading the revolver. The distance from the back of the barrel lug to the top cylinder chamber was bridged by a forcing cone that was nearly flush to the cylinder, as shown on a Colt 1851 Navy (bottom). In 1858 E. Remington & Sons introduced their Navy and Army model revolvers (top) which used a solid topstrap frame with the barrel threaded into the frame.

When the Colt’s revolver patent expired in 1857, E. Remington & Sons became the first major American armsmaker to introduce a competitive large caliber pistol. The design of their 1858 Remington-Beals Navy and Army models eschewed the prevailing Colt design by using a solid topstrap frame with the barrel threaded into the front of the frame.[1] This was a stronger design than the Colt. And this is where the first confusion began.

Close-up shows the forcing cone at the back of the Colt 1851 Navy barrel.

Close-up shows the forcing cone at the back of the Colt 1851 Navy barrel.

The forcing cone for the Remington Navy and Army models was actually the back of the threaded barrel which passed through the frame and ended just in front of the top cylinder chamber. This is the back of the barrel and the point when one begins measuring barrel length.

The forcing cone for the Remington Navy and Army models was actually the back of the threaded barrel which passed through the frame and ended just in front of the top cylinder chamber. This is the back of the barrel and the point where one begins measuring barrel length.

Folks started thinking that the barrel was measured from the front of the frame, but the threaded end of the barrel’s bore continued through the frame, and ended directly in line with the top cylinder chamber, where the forcing cone came up almost against the front of cylinder. The forcing cone was necessary to provide as close to a solid seal between the back of the barrel and cylinder chamber as possible in order to prevent gases generated by the ignition of the gunpowder in the chamber or cartridge from escaping; simple enough again, unless you mistakenly begin measuring the barrel from the front of the frame, and not the front of the cylinder or the back of the forcing cone. And you would be amazed how many people have made that mistake over the last 158 years since the first Remington revolver was built! It is still a problem, and it has happened as recently as this month with the confusion over the new Umarex Colt 7-1/2 inch barrel CO2 model. On the box it states “BARREL LENGTH: 6.75 inches.” Did Umarex and Colt get it wrong? Depends upon what you are measuring, and how.

Colt Peacemakers (a copy of Bat Masterson’s 5-/12 Colt SAA top) and the Umarex Colt .177 caliber air pistols both use a forcing cone at the back of the barrel to create the seal between the front of the top cylinder chamber and barrel breech. Again, this is the point where barrel length measurements begin.

Colt Peacemakers (a copy of Bat Masterson’s 5-1/2 Colt SAA top) and the Umarex Colt .177 caliber air pistols both use a forcing cone at the back of the barrel to create the seal between the front of the top cylinder chamber and barrel breech. Again, this is the point where barrel length measurements begin.

Let’s jump back to 1873 when the Colt’s Patent Fire-Arms Manufacturing Co. officially introduced the Peacemaker. It was patented in September 1871 by William Mason, Colt’s Superintendent of the Armory and the first examples were built late in 1872. The first Colt Single Action Army revolvers had 7-1/2 inch barrels just like the latest .177 (4.5mm) caliber Umarex Colt Peacemaker pellet models. So where does the confusion about a 6.75 inch barrel length come from?

The recessed inner .177 caliber barrel sits back from the .45 Colt muzzle by 5/16ths of an inch on 5-1/2 inch models and 11/16ths of an inch on the 7-1/2 inch models.

The recessed inner .177 caliber barrel sits back from the .45 Colt muzzle by 5/16ths of an inch on 5-1/2 inch models and 11/16ths of an inch on the 7-1/2 inch models.

It’s a little ironic that the method used for measuring the barrel length of the new 7-1/2 inch pellet model Peacemaker is unintentionally taken from the front of the frame to the muzzle, which is 6.75 inches. But that is not the reason the gun is listed as having a 6.75 inch barrel. In order to have an accurate copy of the original .45 Colt SAA model, the barrel has to be 7-1/2 inches measured from the muzzle to the front of the cylinder, and the Umarex Colt is within 1/16th of an inch because the forcing cone for the airgun is a little shorter than a cartridge gun’s. But, and here it comes, the .177 caliber rifled barrel for the revolver is recessed inside the .45 Colt barrel by 11/16ths of inch. This totally hides the .177 caliber barrel’s muzzle, so the gun looks like a .45 Colt. When combined with the slightly shorter forcing cone, the actual internal length of the .177 caliber rifled barrel liner is, wait for it, 6.75 inches (or within a very small fraction of that measurement). So both numbers are technically correct!

This diagram of the new 7-1/2 inch Umarex Colt Peacemakers (with the optional white grips) shows the measurements of the outer full length, and recessed inner barrel.

Photo of the new 7-1/2 inch Umarex Colt Peacemakers (with the optional white grips) shows the measurements of the outer full length, and recessed inner barrel.

If you are wondering about the current 5-1/2 inch barrel length Umarex Colt Peacemaker models, their .177 caliber barrels are recessed 7/16ths of an inch back from the .45 caliber muzzle. Not as deep as the 7-1/2 inch models and their overall exterior barrel length is also about 1/16th of an inch short of a .45 Colt 5-1/2 inch barrel. If you look at the box on the 5-1/2 inch models it reads “BARREL LENGTH: 4.5 inches.”

So, Colt Peacemaker fans, take your measurements the same way Sam Colt did back in 1847, from the muzzle opening to the front of the cylinder, and never mind what the box says! We’re talking 19th century authenticity here, not 21st century accuracy.

[1] Samuel Colt’s Superintendent of the Armory, Elisha King Root, patented a sidehammer revolver with a solid topstrap in 1855, which Colt introduced as the Root 1855 Sidehammer Pocket Model. The small .28 and .31 caliber pistols remained in production until 1870.

18 thoughts on “The Colt Peacemaker barrel length conundrum


    • I like the bigger grips that come on these co2 versions; fits my hand much better. I just ordered the 7.5 barrel and am looking forward to ordering the Schofield in Nickel.


  1. Any way you measure, a nice looking hog leg! By the way the engraved 45 BatMasterson which I believe I recognize as a Pietta from a Guns of the Old West article , looks like a gun to copy as a Umarex Colt Lawman revolver. Just saying.


  2. I don’t have a lot of experience with CO2 pistols. The 7.5″ Peacemaker is the quietest of the few I’ve owned. It does not have the longest barrel. Any idea of the reason behind the lower sound level? I have not shot it over the chrono yet but it seems to have good power.


    • I have not tested the 7-1/2 inch model yet, but the Peacemakers are not as loud as some other airguns and that is probably due to the individual cartridges. I will be doing a full test and chronograph of the 7-1/2 inch model next month. The loudness rating is 4-Medium-High, but I find them more toward the medium. I will look into that though and get a more definitive answer with the 7-1/2 inch Peacemaker test.


  3. I found a handy thing with the Peacemaker. From time to time I have wanted to change a low co2 cartridge before it is empty. This is the easiest gun I have found to empty the co2 cartridge. Remove the shells. Then lower the hammer. Do not release the hammer, keep the trigger pulled. Then just push the hammer ahead. It will contact the valve and release the gas.


    • Haven’t tried that either, hardly ever run out of BBs and shooting time befre the CO2 is exhausted. My only concern is too much air escaping at one time by pushing the hammer forward and letting it all escape at once. I’ll check with Umarex to see if that is a safe practice and does not potentially harm the seals.



    • Right now no blued 7-/12 inch guns are in the pipeline that I am aware of, only the nickel and the weathered finish guns that are exclusively for the NRA model sold by Umarex. Nickel seems to be the most popular because the finish is more accurate to original guns, while the blue isn’t a real Colt blue. A weathered finish would actually look better than blued.



      • A blue finish like the original blued bb versions with a case colored frame and loading gate would be a real winner. It would not be easy but it could be done. Would be a great variation


        • The blue finish is harder to do on an aluminum alloy, as traditional bluing does not work the same on alloy as steel. Color casehardened frames and hammers are also not possible because of the temperatures needed. Faux case colors are possible, but are not lasting over time. That’s why the weathered blue steel look is so appealing, and of course, you can never go wrong with nickel.


        • One more point on the early blued Umarex Peacemakers. The finish was not consistent, (I know I have one) blue and purple tones mingled and they were not all the same. And as I have mentioned before, the blue black finish on the excellent Umarex Walther P.38 is not the right blue for a Colt SAA so no point in going there. Blued guns are great but for the Colt SAA airguns I have to stand behind nickel over blued.


          • The early blued Peacemakers almost looked like 2tone alloy frame Rugers I liked the pseudo casehardening you did on the Schofield hammer.Always liked blue / casehardening onsingle actions I had twoRugers casehardened to look like Colts.Can never go wrong with nickel finish Peacemakers


  4. The later 22 Colt Scouts used a similar heavy alloy frame , Zamac. The P 62 blue versions looked like a painted finish that wore poorly and peeled off . The nickel K Series in held their finish . The later 22 Peacemakers were steel frame and used the same alloy back strap and trigger guard , and the frame was casehardened like the center fire version. I would like to see a steel frame blue and case hardened frame in a 177 pellet Umarex Peacemaker, even in limited numbers like the engraved revolvers . I believe that discriminating airgun shooters would pay for such a revolver . I certainly would.


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