Yes Colt makes the 6450, I've got one that was made in 4/05 and I bought it in 5/05. So far I've put 3,500 rounds through it and it has yet to jam. The mags that I use are the 32's that came with it and pre-ban factory 20 rounders (btw 20's are hard to find) plus the cheapy Promag 32 round plastic mags. The Promags have worked fine so far, although they tend to swell like the older Glock mags that weren't fully metal lined. So they fit tight in the mag well, they do hold the bolt on the last round though.
The only trouble you have is not having enough 9mm to shoot, it loves WWB 100 round value packs. Oh and the 9mm gets very dirty, much more than a 223.
I've bump fired it before and it will burn through a 32 rounder in under 2 seconds
The 20 rounder went so fast I couldn't take a good digital picture of it, I had to use the 32 round mag instead.
That's the beauty of 9mm....very cheap compared to 223.
I traded a MT6551 for my AR6450 so I didn't pay full price but list price was $1,195