Usually I always carry in my car a borelight, a magnifying glass and few tools, just in case i come across an interesting buy.
Things I look for:
- Rifling and crown (obvious)
- Any loose piece of furniture, parts, etc... other than normal wiggle and rattle in some type of action (pumps for example)
- I try to take it apart as much as I can, if the owner refuses, I walk away.
- I hate missing parts, even the most insignificant non crucial ones (for example, iron sights if there is a scope), it is a pet peeve of mine
- The stock has to fit me right
- Straight barrels/stock, canted sights.
- How smooth is the action...any impediments??
- Deep rust...I do not care for the occasional surface spot, scratches/fading in the bluing, dings/scratches in the wood...if the price is right.
- Look for even the tiniest cracks (both metal and wood)
- Any misalignment or forced match of stock with the action and barrel (for example poorly sporterized military rifles or milsurps put together from cannibalized parts) and I walk away....if is a milsurp, I want matching numbers at least of the most crucial parts (for example receiver and bolt)
- With a screwdriver, I try to verify if there are stripped screws (in particular stock and butt plate/recoil pad)..it happened more than once that I unscrew the butt plate/pad and the screws were literally wrapped in electrical tape or regular scotch tape to fit in big stripped screw holes or. worse. a cracked stock.
- Overall you can see if the gun has been well taken care of even if used in a harsh environment.
- Take your time...do not rush
- I try to verify on the spot (if is a gun shop) the headspace,,,if i cannot, I try to negotiate a few days of return window if the headspace is excessive or cycling issues with live ammo.