So the concept with the MMAS is fairly simple. The fins have a notched step that marry up to the notches in the rings. The aft ring gets T-nuts and the holes in all the adapter rings line up. So they'll all bolt right in place. The forward ring doesn't have notches just holes cut for a pair of U bolts. The 5.5" should only stick out about an 1/8" after glue. But that's all in the instructions. If you look at the Rockets of high power calendar, April. That was the first "Large" kit we did this set-up in. Held up fine for a 98mm CTI 5-grain and a 100 pound rocket. But the real purpose is to be able to switch to whatever mount you'd like. And if you're not 100% sold on the bolt in concept, any adapter can be permanently mounted.
I hope that adds some clarity?