I recently purchased my first AR, a Bushmaster Dissipater. Love the rifle, shoots great; only down side is that it’s HEAVY! With the heavy barrel and the 12” free float (to cover the pin hole where the forward site post used to be) plus the optics and so on, it’s a bit too much. I want to change over to a 16” light weight carbine barrel to cut down on some of the weight. Will any 16” lightweight carbine barrel work or do I need to get something specifically for my upper (sorry for ignorance here, I’m new to the builds). And will I have any issues with cycling and so on since I’m going from a mid-length gas block to the carbine length? Thanks fellas. III%

The answer to your question is that any barrel with fit your upper receiver but the down side is that the dissapator runs a rifle length gas tube and handguards...

You will have to buy a gas tube to fit what ever barrel your buy?  example:  if you buy an ARP mid-length lightweight you will need a mid-length gas tube and then handguards or if you buy a carbine length barrel you will need a carbine gas tube..THEN you need the right handguards for what length gas tube you end up with.  OR you can just get a low profile gas block and run a freefloat tube....there are some cheap imports on there for a reasonable price and they work fine...Ive got one coming that 10" in length that will cover up the low profile gas block on my carbine barrel...I paid $56.86 delivered.

If I knew how to put a photo on here I would show you what Im working with, I already have a MI 12" free float installed over a low proflile gas block, so that part is already done. Just going to pick up the 7" MI free float and swap it out once I get the new carbine barrel. Will a 7" free float cover the gas block on the carbine barrel? Just wanted to make sure it was as easy as i thought to swap the barrel. Thanks!!

You can use the 12" FF rail on a carbine length system, no need to get a carbine length rail unless thats what you want. Also, when you go to a lightweight arrel youll need a new gas block since the barrel profile is smaller, usually .625".

12" will leave you 4" of barrel on a 16" barrel...plus the muzzle brake...  If you already have a low pro gas block....just get whatever barrel you want along with a gas tube and use your free float tube.  

ARP AR Performance light weight barrel has a .750" block which is the normal size on barrels....


even if you get an m4 regular profile with your parts it will ighten it up aloot.