OLD COLT: WE PROVIDE THE PUBLIC WITH AN ONLINE EDUCATIONAL RESOURCE FOR OLD COLT GUNS.
.22LR - .45ACP Colt Conversion Unit for M1911 & Government Model
| Year | Approximate Serial Number |
| 1938 | U1 |
| 1939 | U400 |
| 1940 | U900 |
| 1941 | U1100 |
| 1942 | U1400 |
| 1943 | U1701-U1750 |
| 1946 | U2001-U2670* |
*Colt Conversion Unit's continued to be produced past this time but this is the last recorded serial numbered unit.
.45ACP - .22LR Colt Conversion Unit for the Service Model Ace
| Year | Approximate Serial Number |
| 1938 | U1 |
| 1939 | U18 |
| 1940 | U61 |
| 1941 | U112 |
