H&R makes a classic single shot that lasts for generations and the price is right. I like these a lot,having started with a 16 ga H&R. But....
First, I'd not recommend a 10 for most hunting,and for most hunters. The H&Rs tend to kick, hard. That's due to the light weight and lots of drop in the stock. Also, there's only one or two areas in all of shotgunning where a 10 is a better choice, long range gunning for big waterfowl and turkey. And both in of those areas the advantage is not that great.
Ammo's not that difficult, but it runs on the expensive side. There's no low cost "Game" or Field loads, that would cut your practice costs.
My guess is, your buddy is getting rid of it because it's loosened his fillings and lightened his wallet.
Unless you're an experienced shotgunner with lots of recoil tolerance, I don't think this will be a good choice...