I would think after 40-50 rounds if something is going to move you will know it by then. Pull the action after that amount and any signs of movement should be obvious.
As far as a torque wrench look at midway or cheaper than dirt. Expect to spend near $50.00 at least. If you go to buy one locally make sure it is INCH POUNDS and not FOOT POUNDS.
Put 65 ft/lbs to actions screws and you will learn words you never thought existed. Or if you want to slide by I will snug them for you for Pepsi moolah.