Looking at a 16" barrel, how much more does the .750" weigh compared to the .625"? Other than weight, is there an advatage of having one over the other?

The .750 is what Del-Ton calls their heavy barrel.

wisconsinteacher:

.750" usually refers to the barrel diameter under the front sight base and doesn't necessarily translate to the overall profile.  You can have an M4 profile barrel that's .750" under the FSB and a heavier profile that's also the same under the FSB.  The more telling measurement is probably the diameter under the handguards.

A .625 diameter barrel however is usually a lightweight all around.  I don't think I've seen a .625 fsb barrel that is heavy under the handguards.

Heavy barrels typically are more rigid, heat up slower, and dissipate heat slower.  Light barrels are less rigid overall, heat up quicker, but dissipate heat faster as well.  In a 16" carbine barrel, I prefer the lightweight.

However, one thing to consider with a .625" FSB barrel is you are somewhat limited in selection of gas blocks.  Especially if you want a gas block with flip sight integrated.

Weight wise, are we talking a few ounces or pounds in difference between the two barrels?

Maybe half a pound for a 16" barrel.

Try the calculator here:

www.ar15barrels.com/data/barrel-weight-calc.xls

The answer to some of your question can be found in this ssssspectacular tthread:  "Do These Handguards Make Me Look Fat?"  

16" M4 profile upper + BCG (.625 under handguards, .750 from FSB to muzzle, and M203 cut-out) = 4lbs 1oz 16" Lightweight profile upper + BCG (.625" all the way to muzzle) = 3lbs 12.5oz

ETA: an M4 profile barrel is very handy, quick, and light and a lightweight barrel is even more so.  Either one would be a good choice.  Personally, my next upper (one day ) will be a Del-Ton lightweight.

Avoid the HBAR, if possible, as it's unnecessarily heavy, IMHO.

The barrel on the middy from Del-Ton is this one:

DTI 16" 1X9 Min-Lenght Heavy Barrel.  Is this going to be too heavy?

Too heavy for what?

I don't know that there's a really good answer, here.  If you can go to a gun shop where they have several different barrels mounted to rifles, and see how they feel to you, maybe you can make a determination.

I will be receiving a 20" HBAR rifle kit from Del-Ton on Monday.  It's going onto a DoubleStar lower that I'm picking up at Knob Creek this weekend.  I'm building this rifle as a recreational "plinker" and a long-range paper puncher.  I don't plan on humping it over the mountains or anything, so weight wasn't an issue.  Accuracy and barrel stiffness was.  I am concerned with balance, though, for the 200yd offhand, and am a little concerned that the barrel might make the rifle too heavy out front.  But, hey, like I said, I'm not concerned with weight, and if I found it to be too unbalanced, I'll just stick one of those lead weights that fit in the cleaning kit compartment of the buttstock!

Anyway, Tuesday, when I have my rifle together, I'll let you know.

Whether or not its too heavy is up to you, some people like a HBAR..I don't. I just sold my Del-Ton mid-length HBAR and swapped out for a LW barrel.

Depends on what you want to do with it.  Plenty have bought that upper and love it!  I just don't care for the extra weight.

If you're punching paper from the bench with a bipod, weight's probably not such an issue.

Shooting off-hand a lot, or planning on humping the rifle through a class or something, and the extra weight could get annoying.

If it were me and I HAD TO HAVE A MIDDY (for whatever reason), I would go BCM, Sabre, RRA, or CMMG where I could get a mid-length government profile (light under the handguards) or a totally lightweight barreled upper.

Any reason you don't just go with the Del-Ton 16" Light Weight Upper or the 16" M4 Upper (both with CAR gas systems)?


ETA: if you're comparing mid-length barrels, there is quite a bit of difference between a 16" HBAR middy and a 16" Government profile middy and 16" Lightweight profile middy:

HBAR middy = .750 for 9" under the handguards, under the FSB and all the way to the muzzle
Gov. middy = .625 for 9" under the handguards and then .750 from the FSB to the muzzle
LW. middy = .625 for 9" under the handguards, under the FSB and all the way to the muzzle

Don't have the exact numbers handy, but the HBAR will be substantially (probably at least a pound) heavier than the others.  

I've got one of the Del-Ton HBAR middy uppers and it's not BAD, per se.  Having said that, I plan on having the barrel turned to a lightweight profile as I'd like to take a few carbine classes and would prefer a lighter rifle for manueverability and to reduce fatigue.

If you REALLY want to make your HBAR feel light, pick up an FAL (with scope) and a full 20 round mag and then pick up the HBAR.  Trust me, it feels light as a feather!

N2CH_556, thanks for explaning the three barrels.  It helps a lot.  I plan on using the rifle to shoot paper and just have fun with.  If I were to hunt with it, it would not be all day hikes.  I just want it to be right when I go to order my kit.  Man there is a lot to think about when planning an AR.  Keep the info coming, so I can make up my mind and then change it a few times, like I have with all the other parts of the gun.  Thanks.

Go with gummint profile.

Unless it is a bench gun or a safe queen I suggest the light barrel.  For most shooters you will never know the difference the heavy barrel will make in accuracy but will feel the difference in weight.  If you are buying a Del-Ton kit you won't be getting a match barrel anyway (not a knock, just saying it is a normal barrel) so go with light.