I understand that Hasbro wanted to add a firing projectile to the AT-DT, but it looks odd without the full length cannon. I added a K’nex and a Lego piece to mine. Not nearly accurate or really a color match, but I think it looks better.
Looks much better with weathering, I've got to try that someday. I'm keeping my eye out for stuff around the house that I can use to make the cannon(s?) longer and more detailed.