The .44 Magnum Smith and Wesson Model 29 was invented during the winter of 1955 and the first one came off the production line on December 29, 1955, notes American Rifleman. The gun was not given the name Model 20 until June 1957.
After the name change in 1957, Smith and Wesson began to stamp model numbers into the metal yokes of all Smith and Wesson revolvers. The Smith and Wesson Model 29 holds six .44 Magnum cartridges. Model 29 barrel lengths range from four to 10 5/8- inches. Model 29 owners looking for other sizes were able to special order barrel lengths or have barrels specially made by gunsmiths.