I want to tap an M12 Bumax fastener (fu = 145ksi, stainless) into a 4" thick piece of machined 6061-T6, and want to be able to develop the full strength of the bolt. The thread stripping calculation requires approx 0.75" of thread length, which is 1.5 diameters, that is to say a lot more than a full strength nut. I am curious about the threads not taking the load evenly, though the aluminum is ductile and in principle should be fine.