The ASG MK 1 is based on a combination of the Ruger MK I-III, it looks mostly like the Mark III since the barrel is fairly stout but it does not have the typical taper near the charging handle area. Still it resembles a Ruger 22LR pistol very much. There is no blowback or charging handle operation so that means that only a double action trigger is possible, this is a bit unfortunate sine the real Ruger Mark III has an absolutely smooth and light single action trigger.