The "butt" needs more room. In the original you could only store one magazine. I'd like to be able to store at least 2 and 50 rounds of ammo.
But, I had one when I had an outboard. Thought it was a good thing, at the time. Now, I'm thinking a cheap handgun (maybe a surplus 9x18) in a watertight, floating bag would have been a better, more effective choice. If there's a sudden threat getting the AR-7 assembled could be an undoing. Plus for self-defense, I'd rather have a 9mm than a .22lr.