I'm about to order a post ban Bushmaster Dissipator upper (no brake) and I'm looking for opinions on whether I should get the HB or M4 barrel weight.  They both cost the same.  I think the M4 version is about a half pound lighter.  I've never thought a 20" HB A2 was heavy though so I don't think I'd think the HB Dissipator was heavy.  I know the advantgae of the M4 is less weight, are there any disadvantages?  Thanks for any opinions.

I would say the M4, I have an HBAR Dissipator and it weighs about 8.5 to 9 lbs. not gonna cripple me or anything but for a duty type rifle that you will carry around...well...I'm almost finished building a lightweight carbine (6 - 6.5 lbs)

I was thinking about buying one of those M4 Dissipator barrels myself. I couldn't find one in stock anywhere, so I called Bushmaster direct. I was told that they only produced a run of 100 of those barrels, they are all sold out, and don't know when/if they will make anymore. So, if you find someone who has those barrels in stock please let me know.  tx50

What about a fluted HB.  It would be 0.5 lb lighter than a 20" HB (close to that of an M4 I think), and is stronger and dissipates heat better than an M4.