I am using a imr 18650 aw and its working great, what brand battery? I cant imagine a situation where that floating pin would not make good contact even with a flat top, but those little magnets work great but I suppose that is what you are waiting for in the mail huh?
edit; I think I can imagine it now, so the postive side of the flat top has a smaller diameter than the bottom of the positive contact post on the ggts? is that correct?