I have one thats chambered for 2 1/2" commercial ammo.
Civilian conversion on a 1918 ShtLE BSA.
It's been re-BNP'd for 3 1/4ton as well and 2 different 410 stamps.
Aprox 6" groups ( standing, unsupported) at 50yd with 2 1/2" slugs and about a 20" pattern at 20yd using shot.
3" shot ammo work very well also , actually better than the 2 1/2" which I've had a few light primer strikes that didn't fire.
The mag is still in place but won't quite feed 410ammo , so I use it as a loading platform only for single shot.