Sounds to me like a great trap gun,for you. I wish more folks would shoot some clays with their HD tool, for familiarity and practice.I use my 21" bbled, Kitchen table built 870 for same.
Is it what a trap fanatic headed for the Nationals would pick? Nope.
Is the bbl about a foot shorter than what most serious trap shooters would use, and is it about a lb lighter? Yep.
But we're talking fun here.
Bbl length,load and choke do matter some, but the shooter is the biggest piece in the puzzle.
I've got HD and Deer 870s, with GR sights and mag extensions. I've used them for clays, at the kind of courses where there's more Beamers and Volvos in the parking lot than P/U trucks,and had a good time and score. I prefer to use my "Bird" 870, mentioned above.
I assume your Defender is a HD tool. If the budget can handle same, why not get another 1300 with a longer bbl, tube chokes,and so on? With the controls all the same,you won't get mixed up in a crisis, and you'll gain familiarity with your HD tool while turning satisfactory numbers of clays into clay powder....