Daniels Defense S2W profile is a tapered profile, its very thick behind the gas block and slowly tapers down to the gas block. I have one of the 16" S2W profile barrels in 6.8 SPC II, but I used an AZ61A Magnesium Alloy handguard to off-set the added weight, so it handles like a typical 16" gov profile 5.56 upper with a typical 6061 T6 handguard (comparable lengths).
36.9 oz for the barrel (ouch!!!) but only 6oz for the 15" mag alloy handguard and 7075 barrel nut = 42.9 oz
I also have a Daniels Defense 16" Light Weight profile barrel in 5.56 (NATO chamber, 1:7). Basically it's Gov. profile behind the gas block, but thinner out front like the original M16 pencil profile. Weighs the same 24oz as a 14.5" Gov profile in the URG-I.
24 oz for the barrel but 14.9 oz for a typical 13.5" Geissele SMR handguard + 7075 barrel nut = 38.9 oz
1/4 lb or 4oz difference is fairly small, most of that being back towards the receiver (due to the barrels profile).
Although a Scout profile 6.8 barrel is 28-29oz, so I could have made the 6.8 upper lighter than even the 5.56 upper. Likewise, with the 5.56 upper, I could have used the lighter handguard paired with the LW barrel for an ultra light setup, but I think it would be too lightweight at that point. I prefer mid-weight guns vs. very heavy or very light.
My goal with the 6.8 upper was to be at a comparable weight to a typical 16" 5.56 setup, but with harder use capability and maximum fire power in an AR-15 frame size, while the 5.56 upper was closer to a general purpose URG-I type setup but with 16" barrel to avoid having to pin the brake. I am quite pleased with both for their roles.
Here is what I got at 50 yards during zeroing of two uppers, both equipped with 1-6x LVPO's from Vortex. Razor HD Gen 2E on the 6.8 SPC upper, Viper PST Gen 2 on the 5.56 upper, both on Badger Ordnance C1 1.70" mounts.
Surprisingly, the scope just happened to be nearly dead on starting out with 6.8 SPC (lucky):
Confirming 10 shot group with 110gr OTM after minor adjustments with VMax (Black) (it's .2 MRAD, so that's about as center as it can get):
Since I ran out of those targets, I did have to use a training target for 5.56 vs. a zeroing target (and it started raining right at the end, so it became polka-dotted), so that MAY have had a small impact on my POA and final accuracy results:
Very comparable velocities, even the BC's were comparable (.363 for 77gr OTM, .360 for 110gr OTM and .370 for 110gr VMax). Same manufacturer (Daniels Defense) of the barrels in their respective calibers, same barrel lengths, same mil-spec forged uppers (squared and bedded), same torque on the barrel nuts (55 ft-lbs with a calibrated wrench), same day, same magnification, same distance, same chrono...you get the idea. I did pull at least one shot on each target due to running out of time and starting to rush. Cadence was about 1-2 seconds per shot, so not exactly eeking every oz of precision either, just practical shooting with decent holds.
Note the upper right circle (last photo) is where I did most of the rough sighting in, then once I got it close to center, I shot the lower left circle (lower left four holes), made one final adjustment and then shot a final 10ish shot group (the center cluster, low left circle). BTW the muzzle velocity for 77gr Razor Core was 2586 FPS average, but I forgot to write it on the target.
These results seem pretty well inline with pointblank's results and the article I attached comparing a Colt SOCOM profile to a Cold Gov profile barrels accuracy seems to further that notion. Not a huge difference for slow fire precision or light duty use at closer ranges. I think the heavier barrels come in to play with recoil (more mass makes for a softer shooting gun) and rapid firing schedules and when pushing longer ranges (300 to 600 yards). Heat is also the enemy of accuracy, hot barrels aren't accurate in any caliber or profile.
Thinner profiles whip more during rapid fire bursts (suppression) weather semi or full auto, while that may not matter when standing (due to recoils affects on POA being far greater), it does start to show up when prone, supported on a bipod, heavy barrels start to really shine. That's exactly why the M27 IAR uses a really have profile between the chamber and the gas block. Less whip, more thermal mass for bursts of fire, while maintaining reasonable accuracy under heavy use but at the expense of weight / balance.
Holy barrels batman, those suckers gotta be nearly 3 lbs! (M27 IAR aka HK416 Heavy Barrel).
So it all depends on what your doing. I will say that heavy profiles are slightly more accurate on average even when cold, but it's only about 1/2 MOA with all other things being equal. If you can afford it, why not have one of each? I really like lightweight profiles in 5.56, it suites the low recoil and weight of the cartridge. I like to capitalize on accuracy and heavy use for more potent cartridges (6.8 SPC, 7.62x39, .308 etc.) or that may see use for game animals as well.
If you roll your own uppers, you can achieve comparable weights by using ultra light handguards to mostly off-set the weight of the heavier barrel profiles, gaining the best of both worlds.