First off, I personally don't think I would base my decision too much on already owning a 22 mag revolver and just buying one type of ammo. It just doesn’t seem like that much of an advantage in this situation to lend much weight to it (unlike 130 years ago when crossing the prairie on horseback with two guns to feed). Second, out of the two cartridges you're considering, I'd probably go with the .17 if prairie dogs are your main quarry. If you were shooting much larger stuff too, like chucks or an occasional coyote, then I would say 22 mag. The 17 will get blown around more from the wind then a 22 mag but shoots quite a bit flatter. The 17 on a calm day will probably shoot better groups but a decent 22 mag can still shoot plenty good enough to do the job within it's effective range. I don't know why the 17 typically shoots better then the 22 mag but if I had to venture a guess I'd say it's because, being so much newer, the dies, tooling and equipment used to produce the ammo are newer, less worn and able to produce it to tighter tolerances. Plus, all of the 17 ammo out there is all top shelf stuff, whereas the 22 mag ammo probably has a broader quality range. Again, this is just a guess on my part. And lastly, I have both and like both however, for the type of shooting you describe I prefer my 22 Hornet over either. Good Luck with your future Pdog rifle !
