I agree, this appears this story appears to be heavily scrubbed\enhanced to forward a Liberal agenda. I don't think a street thug would care about specific politicians, bills, and ect and he is very specific. The M16 is also confusing, as it's highly unlikely to be obtained via a straw purchase as his blog suggest. However it does point to a gun-ignorant activist author. Even if we assume it was a AR15, his booking date (Linked in story) was 2-2004. The AWB didn't sunset until 9-2004.
TTP: It doesn't matter who wrote this. Since the rifle he used could not have been obtained via a legal purchase, his entire theory of "If I couldn't get a gun, I wouldn't have commit the murder" is completely worthless.