Right now I think it's something like:

M4 < Govt < HBAR < Bull

But, isn't there something called a pencil barrel?  And what about dissipators?  And I think I've seen 16" barrels with FSBs at different positions.  I'd really like to see a layout of which profile is heavier than the next.

I've seen the info from Bushmaster, but would like a wider comparison.

Thanks!
Jim

ETA: Post number 556!!

The original profile was thin.  It is generally referred to as an A1 profile when the barrel is the original 20" barrel length, but is also referred to as 'pencil'.  Bushmaster calls their 16" pencil barrel a lightweight.  I don't have the exact numbers in front of me but it is very small.  It even uses a different sized front sight base.

The military later switched to heaver A2 profile.  This is what is generally meant by a government profile, especially on 20" barrels

The M4 profile is basically the same as the government profile except that it is used on carbine barrels and has the extra cut out front for the grenade launcher.

Some companies started producing the HBAR barrels, which look like a government profile until you remove the handguards and see that the manufacturer saved money by not reducing the profile under the handguards.

A2, M4, Govt, HBAR and pretty much everything else use the same size front sight base/gas block.

Then there are bull barrels that are heavy along the whole length of the barrel.  These also use a much larger gas block/front sight base.

Edited to add the SPR profile, which is heavier than the govt profiles but lighter than an HBAR.  

That is some excellent information, thank you.

Just to clarify one point, am I right to assume that the diameter of the A2 barrel is the same under the handguards as it is in front of the FSB?

So, we can rank the barrels by weight as follows:

A1(pencil) < A2(govt)/M4 < SPR < HBAR < Bull

For this to hold true, you must assume same length for all barrels.  

Excellent.  

Quoted: Just to clarify one point, am I right to assume that the diameter of the A2 barrel is the same under the handguards as it is in front of the FSB?

No you are not right to assume that.

The part under the handguards is thinner (about .1" diam ) than the part foward of the FSB.  Just like with M4 barrels.

A1(pencil) < A2(govt)/M4 < SPR < HBAR < Bull

Very good I'll go 1 better

A1 < M4 < Govt Profile (no notch) < fluted HBAR < SPR < HBAR < Bull

assuming barrels of the same length.

Correct me if I am wrong, but Bushmaster supplies most of their rifles with HBAR barrels? What are the advantiges to an HBAR over a GOVT profile?

Thanx.
Sammy

Apparently the cost to produce is lower and it makes for a stiffer barrel under the handguard.

Quoted: Correct me if I am wrong, but Bushmaster supplies most of their rifles with HBAR barrels? What are the advantiges to an HBAR over a GOVT profile?

Cheaper to manufacturer (less machinging time required).

The HBAR is better if you like to use your full auto to unload Beta mags down range with a single trigger pull.  Thats about the only benefit.

Thanx.
Sammy