The 1/2" guarantee is a bit bogus. In order to shoot 1/2" consistently, you need to use a rest, and the stock in this unit (or any AR clone) is not conducive to being shot off a rest. The trigger has to be very consistent, as does your hold, and the scope has to be top-drawer and stress-free. Everything has to be just so...
The autoloader, by it's very design, won't chamber a round the same way every time either, and the magazine won't allow you to seat the bullets to within .020" of the lands, as needed.
Let's be honest here - besides the fact that this isn't a bench gun, and you pretty much need to bench shoot for 1/2 MOA or better groups, in a practical situation your hold and skills are the true limiting factor.
When LB, Cooper, Kimber, Nosler, Spencer, Borden, etc...guarantee 1/2 MOA, they shoot it from a machine rest or bags, and single-load the rounds so that they can seat them out to the lands. They typically shoot several groups and send you the 'good one or two', not the 4 or 5 other ones that shot MOA or larger.
That being said, you'd have to shoot the thing under practically 'BR' conditions to get that group size, and it wouldn't be consistent.
I wouldn't pay a premium for a guarantee that couldn't be reproduced in field conditions.
I have been a gunsmith for over 15 years, and have built many a rifle, including 1/10th inch group LV/HV benchrest guns. If you want a 1/2 MOA rifle, you are looking at a bolt gun with a premium barrel, and stock that will ride bags, and a trued action. For the 'black rifle', 1 to 1.5MOA is what you can expect for a consistent group size/accuracy level.
I'm not trying to pee on your parade, I just don't want to see you spend a premium and be bitterly disappointed, or burn up the barrel in frustration shooting group after group that doesn't ever measure up.