In many ways the Standard model is a groundbreaking design, lacking the slide found on conventional pistols, instead it sports a cylindrical bolt which cycles inside a tubular receiver in a manner more characteristic of a rimfire rifle. The bolt of the pistol features protruding “ears” at its rear which are grasped and pulled rearward to feed the initial round and cock the action. Using the basic blowback form of operation, the Standard model originally came with a blued carbon steel finish and was equipped with a 4.75-inch (12.1 cm) tapered barrel.
The magazine held 9 rounds of .22 Long Rifle ammunition and was held in place by a catch on the bottom of the grip frame. Standard models came with Patridge style fixed iron open sights with the rear sight securely mounted in a dovetail. The grip panels were hard black checkered Butaprene synthetic rubber, with pre-1950 pistols featuring the “Red Eagle” trademark as originally designed by Alex Sturm. The manual safety on the Standard model could only be engaged when the pistol was cocked, and the bolt could be locked open by activating the safety with the bolt held back.
The bolt was left “in the white” with the unfinished steel providing a visual contrast with the blued receiver. In 1954 a new model with a barrel length of 6 inches was added to the Standard lineup. In 1971, one of the few engineering changes ever made to the Standard model took place when the original 22 year old receiver forming dies wore out. As a precursor to changes to come with the 1982 introduction of the MK II series, the slot for the magazine follower extension on the grip frame was moved from the right to the left side.
Designated the “A 100” frame modification, this alteration facilitated the eventual improvement of the Standard pistol by the addition of a bolt hold open device as part of the eventual MK II upgrade. The pistol grip panels and magazines from older Standard models can not be used on post-1971 pistols due to this change, but the later magazines can still be used on pre-1971 guns by moving the magazine follower button to the opposite side. As the Standard model reached the end of its product lifecycle in 1981, a special edition run of 5000 4.75-inch pistols built of stainless steel were manufactured. These pistols were shipped in special wooden cases and featured an engraving of Bill Ruger’s signature.
Introduced in 1950, the MK I Target model was basically the same as the Standard pistol, except that it boasted a 6.875-inch (17.46 cm) barrel, adjustable target style trigger, a “Micro” adjustable rear sight, and a front sight blade undercut to reduce glare. In 1952 a 5.25-inch (13.3 cm) barreled version of the MK I Target was added to the lineup, but manufactured only through 1957, making it a collectible rarity today. A 5.5-inch (14 cm) heavy bull barreled version of the MK I Target became available in 1963, eventually becoming the most popular length for Ruger Target MK pistols. Like their Standard model brethren, target models underwent the A 100 grip frame redesign in 1971. The Mk. 1 was later replaced by the more popular models, the Mk. 2 and Mk. 3.