Way to go Carl! I've noticed over the past couple years that the two adaptors I had (both the first gen and now have what, the fourth?) would be difficult to remove from the tank for transport. I used a fine file and filed the edges of the bottom and that greatly increased the ease of use.
Anyways, my real point is, I don't suppose you thought ahead with the bore gauge by making it keychain compatible? I firmly assume you did. Heck, funny would be to polish it up nice and shiney and disguise it as "airsoft bling" to put on a neck chain. Lol