Get a longer barrel for your 870. 28 is plenty, if you're really serious go for 34. You might try trap shooting first, (at the other end of the range) they throw singles and it will get you familiar with the moving target. It's definitely a lot of fun I don't think you'll be disappointed. BTW- there is a guy that has been state champ in sporting clays several years running, he shoots and 870 with a 34" barrel. My co-worker is big in to this sporting clays stuff, he has a $7500 Perazzi, but keeps an 870 for a back up.