All original, good condition, U.S. Cavalry and Artillery Single Action Armies (those produced between 1873 and 1891) are among the most valuable to collectors.
Especially valuable, often going for well over $10,000, are the OWA (Orville Wood Ainsworth) and the rare Henry Nettleton inspected Single Action Army Colts.

The OWA Colt refers to the earliest issued Single Action Army guns, which were inspected by Orville W. Ainsworth.
Ainsworth was the ordnance sub-inspector at the Colt factory for the first 13 months (October 1873 to November 1874) of the Single Action Army's production.
It was Ainsworth who inspected the Colts used by Col.
G. A. Custer's 7th Cavalry at the Battle of the Little Bighorn.
The number range of possible Little Bighorn Colts is 4500–7527.

Henry Nettleton was the U.S. Principal Sub-inspector in 1878 at the Springfield Armory.
Second only to the OWA Colts, Nettleton Colts are prized by serious collectors.
Both the Nettleton and OWA Colts have the cartouche (OWA or HN) on the left side of the wood grip.

By the mid-1870s, the Army had purchased a significant number of Smith & Wesson Schofield revolvers chambering a shorter .45 round.
Logistical problems arose because the ammunition was not interchangeable.
The Colt revolvers would accept the shorter round, but not vice versa.
For a time, the Government stopped orders for the longer Colt cartridge and used the Smith & Wesson round exclusively.
The Schofield was soon retired and sold to the civilian market.

The largest group of U.S. Colt Cavalry revolvers was inspected by David F. Clark, his D.F.C. cartouche being encountered on revolvers inspected from 1880 to 1887.
During 1893, the .45 U.S. Colt Single Action Army revolver was retired by the Cavalry and replaced by the .38 caliber Colt Model 1892 Double Action Army revolver.
The .45 Single Action Army revolver was still standard issue to the Infantry, Artillery and other branches of the U.S. Army.

In 1895–1896, the U.S. federal government returned 2000 SAA revolvers to Colt to be refurbished; 800 were issued to the New York Militia with the ​7 ¹⁄₂-inch barrel and 1,200 were altered to a barrel length of ​5 ¹⁄₂ inches.
In 1898, 14,900 of the SAA revolvers were altered the same way by Springfield Armory.
The original records of the War Department do refer to these revolvers with the shortened barrel as the "Altered Revolver".
The name "Artillery" is actually a misnomer, which Sapp speculates may have originated because the Light Artillery happened to have the first units armed with the altered revolver.

The Artillery Single Actions were issued to the Infantry, the Light Artillery, the Volunteer Cavalry and other troops because the standard issue .38 caliber Colt M 1892 double-action revolver was lacking in stopping power.
For that reason, the .45 Artillery SAA Revolvers were used successfully by front troops in the Spanish–American War and the Philippine–American War.
Theodore Roosevelt's Rough Riders charged up San Juan Hill wielding the .45 caliber Artillery Model.

The Artillery Model usually had mixed numbers.
It can be identified by the U.S. on the frame, the inspector's stamps on different parts (such as a tiny A for Orville W. Ainsworth, DFC, HN, RAC for later inspectors and K for replacement parts) and the cartouche of Rinaldo A. Carr (RAC), the inspector who inspected the refurbished guns, on the grip.
All original, good condition, U.S. Cavalry and Artillery Single Action Armies (those produced between 1873 and 1891) are among the most valuable to collectors. Especially valuable, often going for well over $10,000, are the OWA (Orville Wood Ainsworth) and the rare Henry Nettleton inspected Single Action Army Colts.
The OWA Colt refers to the earliest issued Single Action Army guns, which were inspected by Orville W. Ainsworth. Ainsworth was the ordnance sub-inspector at the Colt factory for the first 13 months (October 1873 to November 1874) of the Single Action Army's production. It was Ainsworth who inspected the Colts used by Col. G. A. Custer's 7th Cavalry at the Battle of the Little Bighorn. The number range of possible Little Bighorn Colts is 4500–7527.
Henry Nettleton was the U.S. Principal Sub-inspector in 1878 at the Springfield Armory. Second only to the OWA Colts, Nettleton Colts are prized by serious collectors. Both the Nettleton and OWA Colts have the cartouche (OWA or HN) on the left side of the wood grip.
By the mid-1870s, the Army had purchased a significant number of Smith & Wesson Schofield revolvers chambering a shorter .45 round. Logistical problems arose because the ammunition was not interchangeable. The Colt revolvers would accept the shorter round, but not vice versa. For a time, the Government stopped orders for the longer Colt cartridge and used the Smith & Wesson round exclusively. The Schofield was soon retired and sold to the civilian market.
The largest group of U.S. Colt Cavalry revolvers was inspected by David F. Clark, his D.F.C. cartouche being encountered on revolvers inspected from 1880 to 1887. During 1893, the .45 U.S. Colt Single Action Army revolver was retired by the Cavalry and replaced by the .38 caliber Colt Model 1892 Double Action Army revolver. The .45 Single Action Army revolver was still standard issue to the Infantry, Artillery and other branches of the U.S. Army.
In 1895–1896, the U.S. federal government returned 2000 SAA revolvers to Colt to be refurbished; 800 were issued to the New York Militia with the ​7 ¹⁄₂-inch barrel and 1,200 were altered to a barrel length of ​5 ¹⁄₂ inches. In 1898, 14,900 of the SAA revolvers were altered the same way by Springfield Armory. The original records of the War Department do refer to these revolvers with the shortened barrel as the "Altered Revolver". The name "Artillery" is actually a misnomer, which Sapp speculates may have originated because the Light Artillery happened to have the first units armed with the altered revolver.
The Artillery Single Actions were issued to the Infantry, the Light Artillery, the Volunteer Cavalry and other troops because the standard issue .38 caliber Colt M 1892 double-action revolver was lacking in stopping power. For that reason, the .45 Artillery SAA Revolvers were used successfully by front troops in the Spanish–American War and the Philippine–American War. Theodore Roosevelt's Rough Riders charged up San Juan Hill wielding the .45 caliber Artillery Model.
The Artillery Model usually had mixed numbers. It can be identified by the U.S. on the frame, the inspector's stamps on different parts (such as a tiny A for Orville W. Ainsworth, DFC, HN, RAC for later inspectors and K for replacement parts) and the cartouche of Rinaldo A. Carr (RAC), the inspector who inspected the refurbished guns, on the grip.
Colt Single Action Army