by Bullseye
All you Ruger Mark I owners; what’s the one thing you wish your pistol would do? How about lock the bolt open after the last shot in the magazine has fired!
This feature is even more important to all of you who shoot Bullseye Competition, since your pistol bolt will remain closed after the fifth round from the magazine has fired. Was it a dud? Or, has the last round in the magazine been expended? Well, the picture at the end of this post will give you a outline for a new magazine follower that will hold your bolt open after the last shot is fired.
It's pretty simple to make a set of these extended magazine followers. I used some aircraft grade aluminum for this project. Take an old regular follower from a magazine and trace it. This will give you the proper feed angle for the cartridge and basic size for the new extended follower. Trace out an extended follower tab directly above the normal follower line; it should be no taller than the width of a single .22 cartridge. Then draw a 90' angled line from the back edge of the new follower tab (top) line downward to the cartridge feeding line from the (old) regular sized magazine follower (bottom) line. This is the edge of the follower that will catch the bolt after the last round has fired and hold it open. Then cut out the 90' notch created by the intersection of the line between the old feed line and the new line. Be sure to round the top back edge of the follower slightly to keep the last round left in the magazine from getting jammed by the new extended follower. Here's a diagram to follow.
Round and shape the new follower to fit into the magazine with a file. Put the fitted aluminum extended follower into the magazine a mark where the magazine button is located when the follower is at the correct height using the magazine slot as a reference guide. A #30 twist drill will create the proper sized hole for the factory button to be inserted.
This whole project took me about three hours to complete using simple hand tools. Most of my time was spent using a hacksaw for cutting the solid billet of aluminum into slabs and then for shaping the followers with a large bastard mill file down to proper thickness to fit into the magazine body.
Once complete, these followers will catch the bolt part way and hold it open after the last shot from the magazine has fired. The user will then have to manually retract the bolt and latch the thumb safety to lock the bolt fully open.
The only drawback is; the magazine will now hold one less round than its regular capacity. For me, this less capacity issue is no problem, since I only load five rounds into the magazines for the sustained fire stages of Bullseye Competition. However not having to dry fire the last shot on an empty chamber is great benefit and gives me tremendous piece-of-mind.
Enjoy!
R,
Bullseye
Only this time I wouldn't be hand filing and I'd cut them out on the mill, would save me lots of labor time. 
