I have never seen the need to alter chokes on a parker. If you need a more open pattern just use spreaders. Problem solved with no long lasting changes. I hunt doves, ducks, clay pigeons, and the occasional covey of quail and all of my parkers are either F and F or F and M. If I need them, spreader loads open em up plenty.

Alternatively, I must offer the insightful guidance of world-renowned double gunsmith Larry Potterfield of Midway USA. He takes these classic Parker barrels and reams them. Like nobody's business:

https://www.youtube.com/watch?v=l6yrnJIyjtU

Yes John that will make it bigger. My interest is making it right after the gun is built. Cutting a Parker barrel would would probably change the point of impact. Either way would mess up regulation. Right?

Bill your post shared your experience and opinion which I agree with. Contrary to some of the contributors understanding, I never recommended anyone should enlarge the chokes on any gun, but understanding that some humans want to refine the performance of their guns, I shared the information I had. Bill, thanks for your contribution.

Next up: Best shot size for pheasants ; - )

7.5 in the first barrel and 5 shot in the 2nd barrel. Just my 2 cents

Ounce of 5s @ 1100 fps, btw.

In any gauge, high antimony 7 1/2's in both barrels with plenty of choke. Period.

So many experts on the subject on opening a choke. What Larry did is fully acceptable method of doing it. Why is it thought it would change the point of impact ? Why would it change the regulation ? He's using two bushing to keep the reamer in the center of the bore. What more could you ask for ? How else could it be done ?

I thought we were discussing shot size for pheasants.
My vote is for 5s in both barrels.