On the 870, a good barrel, plus 2 mag extension, and upgraded sights are the first thing I'd change. Maybe the extractor too.
I bought the police walnut model with 18" IC barrel and tritium rifle sights. No complaints and haven't wanted anything more.
This.
And you might want a cylinder bore barrel if you're going to shoot slugs.
870 and 500 are solid guns. You will be a little slower than semiauto.
