ruger MK1

Question
Hey Sid I was just wondering if you know anything about a Ruger .22 LR Pistol.I just bought one that according to the serial number it was made in 1964 and I am not sure if it is a MK1 or a standard because it has neither stamped on the gun.I am having a problem with it jamming.It is very clean and lubed so I thought it might be the mag.If you have any info on this gun I would appreciate it,thanks Keith.

Answer
Keith,

There were many variations of the Standard Model, but basically it featured a 4.75" tapered barrel with six groove 1:14 twist rifling. It came with a dovetailed rear sight mounted on top of the receiver so it didn't move during firing. It had a nine shot magazine without a automatic hold-open after the last round was fired. The safety could only be placed on with the pistol cocked.
The grips were checkered black rubber with the left side having the "Red Eagle" emblem. The logo was changed to black after the death of Ruger's partner (Sturm) in 1951.

The MK1 was the first major change in the S.M. which began in 1951. The 5.5" bull barrel MK1 was introduced in 1963.

The differences between the S.M.(Standard Model) and the MK1 were in barrel shape and length and type of sights. In 1971 the cut on the bottom of the grip frame where the magazine follower button fits was on the left side. The new frame was designated the "A 100" and was stamped with same under the left grip panel.  

As for it "jamming".. I'm not certain exactly in what fashion that it is doing so. It could be a failure to feed/ramp the second round either due to the ramp being ultra rough, or the ammo will sometimes be the culprit. It could be a weak spring or as you indicated, even a magazine problem.

It is difficult for me to give you much more on this without being able to inspect the gun myself. If you have already addressed these possibilities and still are having a problem it may be time to get it into the hands of a qualified pistolsmith for inspection.

If I can be of any further assistance just let me know. I hope that I've aided you somewhat in your quest for information.

Thanks for the question Keith.
Sid Lark