I just moved and I am still working on my home ISP and here at work there are many webpages I can't access because of the firewall. I am just glad I can get in here!
So, Bushmaster says....
14.5" - M4 Bbl. - 2.0
14.5" - Heavy Fluted Bbl. - 2.2
14.5" - Heavy Bbl. - 2.5