[Big Az Al]

I would have a custom made but similar POWER CHOKE made.
The Power Choke has an extended tube that closes the gap the CUTTS has the shot jump across.
The longer tube will fit 20 guage choke better, but it, the longer tube may give a chance to fine tune patterns better.

My 2cents

Al

 

[Big Az Al]

I have seen only a few, when a friend that had bought a Win Model 12 20ga with a nearly factory Cutts but no chokes for it we put our heads together and came up with enough information to turn a choke that looked like a Cutts out front but a PowerCustom inside the baffle portion. He never let me shoot it, but said his son-in-law was shooting lights out with it.

In the process of researching for what might be available we came acrossed several old magazine articles that made claims that large gap through that trash can sized Cutts expansion chamber was letting plastic cup wads expand to the point of catching on the choke attachment, destroying the choke. A reason why so many Cutts Compensators don't have the choke. That is why the Power Tube design was incorporated into the choke tube we turned. We kept the gap to about .375 inches (we could have closed gap all together but why waste some compensation?) with a large funnel section to keep the wad cup intact.

Any lathe jockey can turn the part.
I don’t have 20 ga choke tooling but it wouldn't be hard to turn the choke leaving the inside the dimensions install choke tubes.

This is why I responded with, "have a part made!" Maybe it solves a problem that only the gun magazine writers of 60 some years ago alleged of. But it is an answer, of atleast sorts.

Al