Colt made over 250,000 of their 1851 Navy cap & ball revolvers, plus another
40,000 made in England. They made over 200,000 of their 1860 Army
cap & ball revolvers. The 1851 model was .36 caliber and the 1860 .44 caliber.
Those two Colt models were used extensively in the Civil War. But there
were thousands more "knock offs" made for both sides of the Civil War.
After the Civil War, I suspect that many veterans took their cap & ball
revolver along with them. Many of those veterans went west, so there
would have been many of the Colts and knock-offs, plus all the other
domestic and foreign guns.
Colt's Single Action Army arrived in 1873. It was the 7.5" model. The
Army ordered the first batch for the cavalry, so it took on the name of
Cavalry model. Many of them were cut down to 5.5", so in 1875 Colts
started making the 5.5" model also. Then in 1879 they started making
the 4.75" model.
Most of the so-called "conversions" were made at Colt's plant with a huge
stockpile of parts they had left from making the 1851 & 1860 models.
I believe Richards and Mason were engineers working for Colt at the time.
They made over 9,000 of the so-called conversions, but ran out of barrels,
so they started making barrels and made over 2,000 more. The 1851
Navy models were converted to accept the 38 caliber cartridge.
I have read that someone who owned an 1851 or 1860 could take or
send it to Colt and have it converted for $5. But after the Civil War,
$5 was a lot of money. When the Single Action Army Colt came out
in 1873 they sold for $16.
Colts made from 1873 to 1941 are called first generation, and numbered
about 350,000. 1956 to 1974 was the 2nd generation, with about 74,000
produced. They started a new series of serial numbers starting with SA001.
3rd generation started at serial number 80,000SA and production
brought the serial numbers up to 99,999 by 1994.
Colt kinda went to sleep at the switch after WWII. But in 1956 Ruger came
out with the Blackhawk and was eating Colt's lunch. So Colt woke up and
went back into production.