I have an old Westernfield 20ga shotgun that has a fix full choke. Is there a way to make this into a modified.

For $$$, You can send it in and get tubes put in, but its spendy. Do you have a local gunsmith? they may have ideas?

I had my Beretta 12ga. reworked to modified. The gun smith just ream it out and then polished the inside of the barrel to the correct size. He did a very good job and it wasn’t as much as getting tubes put in as mentioned. Check with your local gun smith. He should be able to help..

Why do you want a modified?

If you currently have a full, the barrel can be honed to any choke you want.....