Never thought to ask.... but at the time, I wasn't even thinking about shooting slugs.
Another tube is only about $80 +/-, IF they even offer one.

10gauge
I understand about the several different brands concept. I don't disagree.... BUT.....
I've got Rem 4/5 oz slugs and Win 7/8 oz slugs.
One or the other will HAVE to work.

AND....
Sixteen ammo ain't cheap. I AM cheap! LOL!
Sixteen ammo is also difficult to locate. Especially slugs and buckshot.