Thanks for all the responses.
The reason I posted this question is that my father in law is considering a target/ occasional varmint barrel for an Encore. He wants dual use with a muzzle loader for the other barrel. He's looking at .223 because it's economical, easy to get ammo and components, reasonable performer, all the usual reasons one looks toward .223. Having had some trouble with my Handis in .223 and having heard that rimmed rules the break open roost, I wanted to ask around a bit and see how other Encore owners do with the round before he makes his decision.
I'll get him to look at this thread before he makes up his mind, which is in no risk of happening too soon.