My HBar Bushy is kinda heavy to lug around for a long walk in the woods. Would I get a significantly lighter rifle by getting one with a fluted barrel or should I just get a 16"? I've read about govt config barrels but have never seen a rifle with one for sale from a major manufacturer.

Bushmaster sells them (govt config barrels) and also the newer 16" lightweight, see them here: www.bushmaster.com/shopping/barrel-assemblies/

Mike

I have a 20" HBAR Bushy and recently bought a light weight 16" flat top upper (similar barrel to the Bushy light weight. It is so light I may never carry my HBAR around again. Another way is to cut down a 20" Govt. profile barrel to 16" and make it like a "Dissipator" type.  I did this with a Tapco Colt surplus M16 upper and it is quite handy. Pics of mine are here:
http://photos.yahoo.com/garymac66

On a general purpose rifle, HBARs are unecessarily heavy. No benefit to all that weight. You could get another barrel, or another upper, or...

You could just send the upper you have to Kurts Kustom Firearms. For a very modest price he will turn your HBAR into something much lighter. He can flute it, or machine it down under the handguards just like the govt. profile barrels. Those 20" Govt profile barrels are lighter than 16" HBARs.

If this interests you, check out Kurt's forum in the Industry section.