I wasn't aware of it until today, ( but I'm sure some of you were) That AAC makes a 3 lug adapter for the Ti-rant 9, and 45, as well as the 45M so you can use it on a MP5. I have 1 on the way :-)
Did you find the AAC mount available somewhere or did you get the J B Tactical. The rarity of the AAC mount and price of the J B is one of the reasons I went with a Multimount.
$300 for the J B Tactical.
http://www.hkparts.net/shop/pc/AAC-Tirant-3-Lug-Adapter-JB-Tactical-p16726.htm