I'd pondered the same issues when wanting to make a set of 22RF barrels to fit my son's 410. Considering the headaches involving eccentrically turning blanks, etc, I finally decided to make them in 25-20 instead. That certainly facilitated also using it as a 410 while keeping pressures low.

I enlisted Ellis Brown of CO to do the excellent work and should have the gun in the white in a few weeks. With his permission, I'll post his in progress photos when it is all done.