I just put a 21" barrel on my M1 benelli Monday. It's wonderful. I can carry it on a sling upside down without worrying about the barrel hitting the ground and getting stopped up with soil when I have to squat or bend down to go under low limbs. Very handy indeed.
I wish they made a 21" for the SBE II, because I'd put one on. Shortest available is 24" but at $500+ not sure it's worth it. The longer barrel (28") and 3 1/2" receiver are ok in the swamp for ducks but "woods" guns with shorter barrels are pretty handy.
