It's been done for some time now. Pick an emery cloth grade that will roughen the choke more than it is now. Test fire; if you want it tighter; more corse grade emery cloth.

The roughened choke will grab the shot cup; separating it from the pellets and producing a tighter pattern. Shot cups pushing the pellets when leaving the muzzle spread the shot more.


Don't sacrifice the future on the altar of today