Also, within a model family the same serial number prefix may be used to produce a variety of different models, all in the same block of serial numbers.
And in some cases, models may be stored for a length of time before they are shipped.
The Ruger 10/22 is a semi-automatic rimfire rifle chambered in .22 Long Rifle cartridges, produced by American firearm manufacturer Sturm, Ruger & Co..
The 10/22 barrel uses a unique two-screw, V-block system to attach the barrel to the receiver, making removal and replacement of the barrel (which would require a gunsmith's work with most other rifles) very easy.
This, when combined with the simple construction of the rest of the components, means that the average person can easily replace any part in the gun with nothing more than a screwdriver, a hex key and simple punches.
The 10/22 is available in a wide variety of configurations.
The standard barrel lengths available for these models were the same as those for the Service-Six, but also included a 3-inch length in certain law-enforcement contract orders, such as for the U.
[The following information is taken from the Ruger #1 Product History web page.] The chart shows the approximate first serial number shipped for the indicated year.