Well that's a lot easier decision. Have him shoot your 20 gauge and see how well he can handle it . If he can, get the twenty. If its too big or kicks too much, get him the .410. If he doesn't want a .410, tell him to wait and save more $. Of course the 20 gauge is more practical to own, but is it the most practical for him? Worst case with the 20 is he will grow into it, and you can use it yourself in the meantime. In NY he still has 7 years before he can hunt deer with a gun (wink, wink). I like the idea of a pump gun for deer hunting, even if it's used.

KEJ