Re: buying a used rifle with issue...
Without seeing it or knowing anything else other than you described it was most likely a pierced primer, the gas traveled through the bolt body and the bullet went downrange as normal. Why the bolt doesn't close is likely inside the bolt. I'd be interested in knowing if putting another bolt in it would cause it to work as it should. Definitely have a gunsmith look into it but like others said the Leupold alone is worth it, on top of that you have a stock, trigger and whatever other parts that are usable that can be sold on ebay.