I have had my Ruger 22/45 for a few years and am just starting to really use it. I bought a Fastfire II site for it that included a Picatinny mount. I mounted the Ruger rail onto the pistol (I had to trim about 1/8 off the front to clear the Williams front sight I have installed).

When I fit the sight base to the rail, it doesn't seem to fit all the way down onto the rail. I think the cross-bolt is sitting too high in the slot in the rail...they seem very shallow compared to other rail slots.

Is this a "known issue" kind of thing? What's the best, fastest, cheapest fix? Deepen the slot? Flatten the bottom of the screw? Different rail?

Rob

What you have is a weaver rail. Order a picatinny rail and you'll be set. I have no idea why Ruger would include a weaver over a picatinny these days, but they do. I just purchased a new LITE model and had the same issue.

I bought a mount for the 22/45 and removed the rear sight and pic/rail. works great and looks much better

 
First reply is right, factory rail isn't picatinny spec, but I would do this ^ myself, and plan to.


 

Just look up Ruger MKIII FastFire mount if you haven't seen it, think it can be found around $30-$40

The owners manual will tell you the mount includered is a weaver mount.  There is a picatinney rail available at shop ruger dot com.  Threaded barrel versions of the 22/45 like the Lite come with the picatinney rail installed.

I did this a couple years ago and love it.