Depending on what scope you get, getting a 20 MOA rail may not be the best thing to do. If all you are going to be doing is 100-150 yard shooting, the 20 MOA rail is going to have most scopes dialed down way into their adjustment range and some scopes don't like being there. They might give you trouble by acting funny in the windage adjustment department.
For 100-150 yards, a plain jane rail will do. If you're on a budget, heck, I've had good luck with the $20 Weaver rails. No, they are not bullet proof, but they do work. How well they will suffer a spill, I'm not to sure about, but they don't work loose if you put them on right. If you're not on so much of a budget, there is lots of good equipment priced in the mid range like EGW and Seekins. If you want to go all out, Nightforce, Badger, etc.
If all you're going to be doing is shooting paper for small groups, you may want more magnification. Although 10X is good for hunting or banging steel, I like to get something in at least the 20X range for paper punching.
You're also going to want something with a reticle that isn't too heavy. In the limited experience that I've had, Burris tactical scopes have reticles that are too heavy for fine target shooting. You might want to check out the Vortex Viper 6-24X. I think they run about $300. You could also take a look at the Weaver T24. It's a fixed 24X, but it's a heck of a target/paper punching scope for the money.
