Here's the problem... the gun is tightly choked now, and the only pellet that really responds to open choke is TM. If you want an open choked duck gun for some reason (like you have the worlds best decoy spread, are a good caller, and have a private pond with no other blinds), then boring it out and spending $1.40/shell on TM is the perfect plan.
If you shoot ducks like most of us do (30 yards is a close shot, and a duck looks real big that close in), then leave the chokes as is and use TM anyway.
Steel through even a cylinder choke shoots at least a modified pattern, so the $500 choking job won't get you a much wider pattern - unless you feed it Tungsten Matrix.
500 bucks will pay the difference between two flats of steel and TM. 500 trigger pulls.
Your choice of course, since you know your hunting situation. I'd love to have the problem of ducks too close...
