Hey dog, sounds like an interesting rifle. MOA at 400 yards is not bad.
If he wants to sell these rifles, he needs to move real slow.
Set up a real business, get a few million in liability insurance, get just all the lawyer work done. If he's anything like many, he doesn't have that kind of money for all the expenses just to do the lawyer/protection stuff.
He needs to not get in a rush to build and sale yet until all that business set up stuff is done.