Sorry I'm a little late in the game, but here's a couple thoughts when buying anything used.
Go in with the right mindset. If I'm actually considering a purchase, I stop admiring what I like about it. I shift gears and start thinking "there are issues with this rifle; I just have to look hard enough to find them."
You'll find some. It's a matter then of whether it'll still make you happy and what price is reasonable.
Besides the bore, muzzle, boltface, I look for signs of abuse (pitting, buggered screws), cracks in the stock (not all are a big deal), etc. It's not really that hard.