I have one of the original "Special Weapons" AR-47s and it is a very fun gun. I have some photos and a review of sorts posted here:
Quarterbore's Forums - Interesting e-mail I just got from a visitor to my website...
It works great and god knows AK-47 mags are cheaper andfar more reliable then any 7.62x39 mags for the AR-15.
Just be warned, I think Special Weapons went out of business and I recall that Vulcan bought the rights to the gun design. I read that the new AR-47s are a ROYAL PITA to get working as the forgings and fitting is very poor compared to the original guns.
I would suggest going to a bigger board, like ar15.com, and ask for recent experience before ANYBODY buys one of the current AR-47 lowers unless you have a ful machine shop and are looking for a project.
Just my oppinion, but carfull as my positive experience is very different then what I have seen posted by others with the current version!