Has anyone converted their 20" hbar to a 16" dissipator?  Can I just get the barrel cut to length and rethreaded?  Would the gas tube and buffer also have to be changed?

Thanks

It would be difficult to do so, but I have seen conversion by Kurt Kustom that will convert a 20 to a dissy.  IK would not suggest doing it yourself.  since you will have to play with the buffer spring and also the gas hole size on the barrel to ensure a proper cycle of the bolt carrier.

Anyone have any experience with this conversion? Did everything function properly?

Aside from the buffer and the upper there are no permanent modifications?

Keep in my the dissipator uses the sghort bbl gas system as well.  

Sell the old bbl on ebay and buy a new one.

bump!

This is a topic that comes up from time to time.
I have done about 4 of these.
You DO NOT have to do anything with the gas port.
Or anything to the buffer, if you use all Colt parts (most importantly the barrel) with a car stock, and buffer.

You don't have to do anything to the buffer.  You do (or should) move the gas port and block back, chop the top so it will fit under the handguards, use a short CAR gas tube and get a new sight tower in front of it.  If you don't move the gas block back, it may function, but it will be marginal.  With some underpowered or commercial ammo you may experience short stroking due to the lack of time between the gas port and the muzzle.  For more reliable performance, you need to increase the amount of gas working on the bolt by increasing the length and time between the gas port and the muzzle.  This can also be accomplished by opening up the gas port a bit, but personally I like to leave everything standard.  

The easiest way to do the conversion?  Sell the 20" and buy a Dissipator.