I'm probably going to be getting a NIB Bushmaster flattop upper for my preban Colt.  Ultimately it will have either an Eotech or Aimpoint dot sight on it with a cut carry handle BUIS.

I'm currently contemplating either the Superlight 16" bbl (the same as my current R6530 upper, which I really like) or the BM 16" M4 bbl.  Whichever I choose will have an A2 FS on the end of it.

Pros of SL:
- great lightweight for carrying.
- no unnecessary metal where it's not needed.
- I prefer function over fashion, so I've never been a big fan of "M4's" and the M4 cut will look pretty old in another few years when the military abandons the cut in favor of RAS II or SIR mounts for accessories.

Cons of SL:
- a little more muzzle flip than an M4 or HBAR bbl (M4 counters it with the extra weight up front, IMHO) -- the M4 is a good compromise between the LW and HBAR bbls.
- I'd have to make a spacer for an M4 side sling mount, same as I did on my R6530 (though that works great).
- heats hasn't been an issue for my with my current LW bbl, but it does heat up pretty quickly.

Anyone have a lot of trigger time on both of these types of bbls or have any thoughts on this?

Well, I have both as well. You pretty much have all the pros and cons sorted out fairly well. Now you just have to decide. My preference in a is the M4, but the lightweight is a great gun too.

Corey,
I was in the EXACT same predicament re lightweight 6530 and M4.  I ended up with a preban Bushmaster flattop 16" fluted upper on my Colt 6601 preban, JP trigger, antiwalk pins and speed hammer, A2 FS, w/ Eotech 552 and ARMS40 BUIS.  I couldnt be happier.  It cools quicker than any of my AR's, noticeably so.  It's handy, and unbelievably accurate way beyond my abilities.  I have had MUCH better luck with the A2 FS, buffer system.  Last week I ran 550 rounds through this setup:  PMP (3 different lots), SB (no explosions, it's old stuff and works great), SA military (3 different lots, and Malaysian.  Nary a bobble.  Sure, that telescoping stock looks COOOL, but it doesnt save me but about 4", is flimsier, not as comfortable, and I've had shorty reliability issues.  Just my ramblings, but I hope the info helps!
cheers, Craig

I have both. If you gotta have the A2 flash suppressor, go for the 16" super light barrel.

The M4 contour is slick if it's a 14.5 incher with a permanently attached Phantom... can you tell where I'm going with this?

My "perfect" barrel would be a 14.5" super light barrel with a perm attached KKF A1 or A2 FS for a legal 16". That's be schweet!

;-D

In a 16" bbl the lightweight M4 Dissipator is hard to beat.  Couple onces heavier because of the extra gas block and full length handguards, but you'll not burn yourself.

M4 + Vortex is my standard weapon though.

-- Chuck

Well . . .
I too have both ! !  (dang, these things are habit forming  ! ! ).  Anyway, I LOVE my little Bushy M-4 carbine (she gets a new Ace stock on Monday  ! ! ) and I installed a Superlight barrel, with M-4 handguards on the carbine my son uses at the local steel plate shoots (son says that the M-4 handguards are the best  ! )
So . . . . my suggestion is to get both  ! !  

I have both, a R6520 govt carbine with the superlite barrel, and a preban bushy with a 14.5 M4 with phantom.   I really like the M4, but the superlite has really become my favorite.
That said, DON"T MAKE ME CHOOSE !!!!
I'll just have both thank you.

Cleophis,

...I ended up with a preban Bushmaster flattop 16" fluted upper on my Colt 6601 preban...

Do you have a 16" HBAR that is fluted or some other fluted barrel profile?  Sorry if I didn't understand your post.

I was thinking a fluted 16" HBAR instead of the M4 profile, and was wondering about the weight difference.

Input from anyone welcome.
Thanks

JCraig,
It's a fluted HBAR.  "They" say it reduces weight by 20% over a standard Hbar.  I don't notice the weight difference as much as the cooling difference due to increased surface area. I'm not easily sold by gimicks, and the AR has PLENTY, but I am sold on fluting.  It makes and looks cool(er), it is 20% lighter, and more rigid than a barrel of the same size and weight (but NOT more rigid than it was before it was fluted).  I find it to be an excellent trade off between weight, rigidity, cooling.  BTW, I know it cools quicker because my HBAR and pencil 16" both have to sit out a bit before I put them in the nylon case.  This one doesnt.  Good luck bro, and hope I helped.
Craig

Cleophis,

Thanks for the reply. I currently have a 16" bull with free-float tube on mine. It's a tack driver but kind of heavy for a just going and wasting ammo. Also it gets hot after rapid fire, very hot! Was looking for a M4 or fluted HBAR version as a second upper for it.

I think maybe the BM 16" fluted HBAR with a carbon fiber tube.

Thanks again,
Jonathan

Jonathan,
You'll definitely notice quicker cooling, and likely notice a bit of a weight difference.  I think the $50 extra for BM fluting is worth it.  Good luck and let me know your impression if you go that route.
C

Cleophis,
Called and ordered my BM 16" fluted HBAR today!  It was in stock and will ship tomorrow!!!



I hope to have it put together by this weekend.  I will post a picture when I've got it up and running.

Thanks again for the input,
Jonathan

Cool (pun intended)!  Let me know how it works out.  Mine is great and I think you'll find it does cool quicker.
Craig