Hiya, I've slightly over pressurised one of my Tilly X246B lanterns, it's now about a sixteenth of an inch off sitting flush on a surface. I think that it's still going to be all right to use just as long as I don't pump too much.
That problem started to happen in the late 1950's when Tilley changed their method of soldering the base plates into the tanks and it has continued ever since.
