Can anyone help me? I have a single shot New Haven model # 273A .410 shotgun that a friend lent me. I know it takes 3" shells (stamped right on the barrel), but I have a question. A friend wants me to use it to go after hogs in our area, and I can't find any 3" slugs. Would a 2.5" slug shell work in this gun, or would I be looking to remove my head if I tried it?

edit: it would probably help if I put the right model number down, it is 273A not 237A