Thanks everyone! This shows how you always learning with Parkers. I mistakenly thought the barrel width at the breach would also be the same across frame sizes. The few times I have tried different barrels they have been on lifters and I never noticed a difference in the barrel width at the breach.
I'll hang on to these and hopefully match them to a Parker someday
Edit: Hopefully, a PH 20 gauge with twist barrels I find at the Southern...