Widder pretty much nailed it as far as what to look for.
The only way to be sure is to test fire it if the owner will let you. Check that a fresh shell enters the chamber with no hiccup as you close the slide at all. And just as important that ALL shells eject well clear of the gun.
If it is brand new It doesn't matter how tight or slightly rough the action is it will break in with use.
If you find an IAC that works well for $500 jump on it that's an excellent price for one that is running right.