IIRC, I was issued a Xm601 back in 2003, then an -A2 in '04. After that GAU-5, and then the GUU-5 in about 2010. 2012'ish we got M4's. And I bitched every second about not having a GUU or GAU. I like them very much especially for what I was doing. I built a GAU-5 on one of the 1:12 barrels in original foil packaging datestamped 1993 from the EE back in 2009ish. It's as close to issue without the fun switch. Also have an m4gery just as I had in the end. And an transitional 604 with mostly all original parts (when you could find the cheaply enough) to represent the first I was issued. That would have been an exact replica if I could have found original green furniture, at the time i found a left green handguard and a green stock, just couldn't find the right so decided not to. Now, I have some of the parts, but not all to do a GUU-5. Also have an M1 carbine, I guess you could say the retro virus hit me hard. =)