You absolutely cannot go wrong with a rimfire for a beginner. It's the right move, as far as recommendations go, honestly, the Ruger 10/22 is the gold standard, period. It's the best overall, hands down. It's affordable, super reliable, and the aftermarket support is massive, which means he can trick it out as he gets more into the hobby. If you're leaning towards a bolt-action for that old-school precision training, the Ruger American Rimfire or the Savage Mark II are both killer options. The Ruger American can even share magazines with the 10/22, which is a nice perk. Any of those will be a fantastic rifle to get him set up properly, good luck to your nephew