You need to look at the Kel Tec .223/5.56 pistol.
It's much the same size as the one you just designed and I'm betting it will shoot better than any version Ruger would make. The Kel Tec's are really great guns for the money, the 5.56 folder will shoot 3/4" groups all day long at 100 yds, so unless you were just hving fun and would like to have a gun like you photoshopped, the Kel Tec is waiting for you now. It takes AR-15 mags, awsome pistol.
Very nice design you made. Maybe you should go to work for Ruger, they need some good help these days.