If it's strictly going to be used for punching paper, I recommend the longest barreled one you can find. The longer the barrel, the longer the sight radius, so the easier it will be to be accurate. Model NR-9L http://ruger.com/Firearms/FAProdView...10624&return=Y
You will also want one with adjustable sights. The shorter barrels can be gotten with either fixed or adjustable.
Again, if you want it strictly for targets, you might think about this. The KNR-7H
You can scope it, or put on a holo sight or a red dot, or whatever.
If you will be doing anything else with the gun - hunting, plinking, just carrying it around - a shorter barrel would be much handier. Barrel lengths are personal, but in a single action I like the 5 1/2".
They used to make the 22s with a Bisley grip. This one is a 45, but the grip is the same. http://ruger.com/Firearms/FAProdView?model=831&return=Y
I've got a couple of them, and I really like the grip.
As to stainless or blue, once again, that's personal. Stainless won't rust on you. Depending on where you are at, that's a plus. But some people don't like the look of 'em.
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