The Ruger Rotary Magazine (also known as the Ruger 77/22) is a bolt action rifle based on the Ruger M77 Mark II. The 77/22 was introduced in 1983 to promote Ruger's innovative rotary magazine (a design which has been intended to improve on the conventional feed system).
The Rotary Magazine was originally based on the Ruger M77, with the bolt action mechanism taken from the Model 77 (which was based on the Mauser 98 action). When the M77 was given an overhaul in 1991 the Rotary Magazine was likewise improved, with the trigger replaced by a two stage trigger, a three position safety replacing the older two tang safety of the original, and an improved bolt. These modifications were originally placed on the M77 Mark II.
The most significant feature of the Rotary Magazine, however, is the mechanism which gives it its name. This magazine is fitted with a sprocket which, when the magazine is engaged, turns via a torsion spring. This mechanism is able to seperate each round, hence guaranteeing a clean feed of the next round. Although this mechanism has been in existance since the late 1890's (the Savage Model 99), Ruger have developed the design to be more reliable and less cumbersome, so as that it cannot interfere with the balance of the rifle.
As with virtually all of the M77 range and its various off-shoots, the Rotary Magazine is fitted with integral scope mounts (located around the receiver) and a variety of both wooden and plastic stocks. Barrel sizes vary between 18.5in and 24in in length while a variety of steel alloys (including stainless steel) are chosen for manufacturing them. All versions of the Rotary Magazine are fitted with basic iron sights (apart from the 17/22 Rotary Magazine, which lacks any sights) which consist of a blade front sight and an adjustable rear sight.
The Rotary Magazine was originally developed to market Ruger's rotary magazine design, hence all models of the Rotary Magazine are fitted with it. The first Rotary Magazine rifle was named the Ruger 77/22 Rotary Magazine and chambered the .22 Long Rifle cartridge (as well as other .22 calibre cartridges). Other calibres used by members of the Rotary Magazine line include the .17 Hornet/.17 HMR (77/17 RM), .357 Magnum (77/357 RM) and the .44 Magnum (77/44 RM).
Various magazine capacities are available but are limited to the size of the cartridge. These capacities range from four to ten each with an additional shot chambered.
The Rotary Magazine was designed to promote the use of the rotary magazine that had been developed by Ruger (although, as mentioned above, the basic design had been around since the 1890's). The success of the design has meant that the Ruger 10/22 (a semi-automatic rimfire rifle) has, in recent years, begun being fitted with the rotary magazine as an option as standard.
As with the rest of the M77 range of rifles, the Rotary Magazine is marketed at hunters and varmiters (hunter's whom persue small rodents). The use of (generally) inexpensive rounds has helped to improve the Rotary Magazine's appeal, despite it's reasonably expensive cost (around $950 depending on model).