Please: this pistol is NOT a "Mark I." Nowadays everyone refers to the Standard as a "Mark I," which is TOTALLY wrong. The Mark I was a target version of the Standard line, with adjustable sights. I blame Ruger for the confusion. The introduction of the modified guns and their designation as "Mark II" regardless of whether they were in target configuration or not, is the origin of the confusion. If a Ruger autoloading pistol has no "scooped out" segments in the receiver forward of the bolt; if it has no bolt hold-back feature; if it uses a 9-round magazine...and it isn't MARKED as a "Mark I," it ISN'T a "Mark I," it's a STANDARD. Umph!