I am probably going to expose my ignorance on barrels here, but...

I am assembling an AR for the wife.  I want it light in weight for her. So far it is an A2 Bushmaster upper, DPMS bolt assembly, bla,bla, bla.

I am interested in a light weight barrel for her comfort.

I have been looking at a CAR 16" (Govt. profile under the handguard) Lightweight, or "pencil" barrel, I believe it is referred to. I have been eyeing an ER Shaw chrome moly chambered in 5.56, if it matters.

I am wondering if that barrel profile suffers from vibration (from a fired round), and heat, ultimately affecting accuracy because it is so small in diameter. It will be used as a plinker for <200 yd. shots at a 5" diameter spinner target.

Would this barrel be up to the task? Would it shoot as well as a heavy barrel or M4 profile provided all the barrels were straight to begin with?

I have a 16" Bushmaster Superlight bbl on one of my carbines. It is very accurate and very light. The bbl heats up a lot faster than my HBARs, but cools more quickly, too. Haven't notice much difference in heat/cool rates vs my 14.5" M4s. All of this is just anecdotal and subjective as I have not actually measured temps/times...

I think your wife will like the setup, but be warned, you'll want one. too...

I have a DPMS flat top with a DPMS chrome lined heavy barrel (no govt profile). I like it but it is too heavy for her. I want to keep this fun for her yet maintain the rifle's accuracy even after 10-20 rounds down the tube.

Well, I guess I should ask what your accuracy requirements/expectations are, but any bbl will heat up with 10-20 rounds in rapid succession. My Superlight seems to stay on target pretty well even after several magazines have been fired. Keep in mind that this profile bbl is like the original contour used for the M16, so you know that it should be "combat accurate" out to the <200 yards, even hot. I know mine does pretty well. I just got it this fall, so I haven't had it out in 100*f temps shooting prarie dogs, but based on what shooting I have done with it, I would say that any p dog within 150 yards would do well to keep its head down, regardless of bbl temp...

If the gun can place them within a 3" circle @ 200 yards, even hot, I will be happy.

Don't get me wrong, I do not intend to melt the barrel, or even see what it takes to influence the accuracy. I am simply trying to gauge how sensitive this profile is under "normal" circumstances.

I used a lightweight "pencil" barrel for a super light buildup on a Cavarms MKII. Grnated mine was not a SHAW but I got rid of it because of functional problems after putting around 2-3 mags through it in succesion. Not rapid succesion, just afternoon plinking at the 100yrd range. The problem was mostly sticking rounds which I think was cause by heat (I changed ammo too including some Black Hills). My thought FWIW is the 16"HBs are sturdy and balance the rifle forward lessening muzzle rise (and add mass for reduced recoil) for the smaller shooter.

First of all, todd: Are you planning on using optics? I use the iron sights on mine and do just fine, but I dunno if I can hold under 3" at 200 yards with them...many AR's will do this, but certainly not all...regardless of bbl weight. I think that would have more to do with the quality of the bbl. I only have one Shaw bbl, a 1:7 that shoots real well, the rest are Bushy, and they shoot real well, too...IIRC, Shaw supplies Colt bbls.

snow: How did you determine in 2-3 mags worth of shooting that your barrel was bad? Never heard of a gun getting so hot that it wouldn't feed...and that doesn't sound like a bbl problem any way...

Sorry.....2-3 mags on several different occasions.

Granted it wasn't a Shaw barrel. But with all AR's I've shot or assembled and shot none had the same quirk as that one did. Checked the gas system as I've had that problem too on a Bushy. Chamber brush with Makita didn't help either.  

Now taking it out and doing about 3 mags, shooting someting else, then shooting it later was OK. Taking it to the range as the only rifle that day was a disappointment. (IE taking my kid out to the range with a nice lightweight rifle and then having it not work)

Not knocking the idea wholly, just saying my .02 experience, (spirit of the board ...and all that)

Here's the deal...

I currently have a DMPS flat top carbine with a DPMS 16" chrome lined 1/9 HB and iron sites. I like it for all around fun at ~200 yards. It runs like a top. Optics and flip up sights may be in its future.

I am assembling 2 more rifes for fun. My first assembly project and I have the tools.  Since I have them they will both use A2 Bushmaster Uppers. I want them in 2 differnt configurations...

One config.  will be more of a traditional build. Mid length, 20" chrome lined 1/7 government profile barrel, and an A2 stock. Why? I can do it cheap right now and I think they look cool without the bling.

The second config. will be for the wife. One that is nice and light (and balanced) yet accurate enough with iron sights for me to be happy. Optics may be in its future too, but not immediately.  It will be a carbine, have a collapsable stock, and 16" pencil barrel. But I better ask the question first... would a 16" M4 govt. profile barrel be that much heaver or any less susceptable to heat than a 16" pecil barrel?

I do not see many of these small pencil barrels so I am questioning it. She does not shoot much but enjoys getting to the range out and plinking.

I have a light weight Shaw on a Colt slabside upper. 1/9 non lined.
Handles great off hand,great balance.
Likes Black Hills blue box.
Not match grade, but with open sights off a bench it will shoot 3 to 4 in groups @ 100.
Might do better with optics and a better shooter, for the $130 I spent I am happy, one of my favoite plinkers.