I have an early 80s-vintage 870 left hand which came with the old 20" smoothbore deer barrel with rifle sights, for shooting Foster-type slugs. It's a fine gun and I've shot a couple of deer with it, but at my age now, iron sights are a gamble.
I also have a Browning BPS pump that I bought new in 1978. Almost 30 years later I put a Hastings rifled slug barrel, with the cantilever scope mount, on it, along with a Leupold scope. I wouldn't trade that gun for anything. I've killed at least 15 deer with it...(and 7 or 8 with buckshot using the original barrel)...it's a deer-bagging machine. Maybe the last gun I'd ever get rid of.