I'm aware of the differences and requirements of AOW and SBS. The MCS units I've seen before come with a shoulder stock that interchanges with the pistol grip and several barrels of different lengths and a carrying case.
I'm sorry, I was not trying to insinuate that you did not know the difference. I too have seen the complete kits with all of the different barrels and stocks. The point I was trying to make is if he bought it as an AOW they would not include the stocks, and the few that I have seen advertised as AOW's only came with the one barrel.