Hey all...my grey and black ultrafires do not fit "tight" in any box mods I've used (BUT YOURS MAY). For all of my other boxes, I've soldered a small bead on the positive internal connection to "raise" the distance a bit. For Old Goat's, I'm using the red flaming Trustfires so its a non-issue. I did pop an ultrafire in though to check and it doesn't quite reach on the old goat, but as I said, they don't reach in any box mod I've used.
For some reason there's a bit of size difference between the ultrafire and trustfire. But if you already have ultrafire, try it and see if the positive end of the battery touches the contact point. If not, it is very easy to use a spacer magnet or drop a bead of solder down to the contact point inside the mod. I think I ordered the last two Trustfires from MadVapes a couple weeks ago
I may have to order some more of these bottom feeders...they are WHAAASOOOME!
ice