Spreaders do work, and you can even make your own if you reload, using the discs from Polywad. Spreaders are not recommended for covey birds like quail. Too much chance of putting a stray single pellet into a bird (or birds) other than the one you're aiming at.

As noted above, if you want the gun for clays (other than trap) and upland hunting with most birds shot inside 25-30 yards, the easiest and least expensive solution in the long run is to have the chokes opened.