The key thing to learn from this post and I am not sure it was stressed very well is that just because a barrel had been "Air Gauged", that does NOT autumatically make it a better barrel.
That just means that it has been MEASURED.
Now, we can only HOPE that the barrels are all measured and the bad ones are rejected, but in the case of most of the low-dollar blank makers, they just set their "acceptable variance" levels high enough that 99% of the barrels will pass.
Companies like Shilen, Douglas, Krieger, Pac-Nor etc... have higher standards on what they let out the door and that's what you are really paying for when you buy a high-end barrel.

Now, if you are buying a barrel and they claim it's air gauge inspected to have less than 0.0001" bore variance from end-to-end, that's useful information.

This is sorta like shopping for motorcycles.
Every maker tells you their sport bike is FAST, but the real question HAS TO BE "how fast"

Quoted: Do the E.R. Shaw barrels fit in the "higher standard" group too. ?

No.
Shaw, Wilson or Adams & Bennet are all "standard grade" barrels.
It's not to say that they won't be accurate, but they are not held to the highest quality standards.
In standard grade barrels, you either get a "hummer" or you get a "bummer"
That's the way it works.
When you spend the money on a top quality barrel blank, you are really just paying to put the odds strongly in your favor that you will get a "hummer" and not a "bummer"
The top makers go to much more work to ensure as perfect of a barrel as they can.
Inspections throughout the process are generally much more involved than the "production" shops like Shaw or Wilson blanks come out of.
The other thing is that with top makers, if they do slip and let a bad barrel go, they will replace it.
Try that with Wilson or Shaw!

Top quality makers are (in no particular order): Douglas, Hart, Krieger, Lija, Lothar Walther, Pac-Nor, Rock Creek & Shilen.
There are lots of other smaller barrel makers that make awesome blanks, but these are the big guys.
Even within those companies, there are different quality levels.
For instance, Krieger and Rock Creek both offer button rifles and single point cut rifled barrels.
Your typical match grade douglas or shilen button rifled blank is no match for a krieger single point cut and hand lapped blank.
If you stay with these top tier makers, you are just about gauranteed the blank will be a winner.
Then it's just up to the guy chambering the barrel to do it right.

Quoted: Quoted: For instance, Krieger and Rock Creek both offer button rifles and single point cut rifled barrels. Krieger makes button rifled barrels?  I've never heard that before.

They call their buttoned product line "Criterion"
I think they are only doing Garand and M1A profiles right now.

Quoted: I noitce that you left a few names that I like/use off of your list of premium barrel makers... Schneider and BJO for example. Do you consider these and some of the even more obscure names sort of "out of reach" in a way? Too difficult to locate or too long of a waiting list to consider primium commercial barrels, perhaps more custom made barrels?

Yes, I would group those with all the smaller custom makers like boots obermeyer, van horn, broughton etc...
BJO = Boots Obermeyer?
Great barrels, but many people have not heard of them and they are not widely known or as easily obtained.

Quoted: Would it be possible for you to supply some detailed information on how blanks are manufactured?  I read your section on how you make barrels and it was very informative; thank you for taking the time to write it.

Here's the quick and dirty version.
You have to talk with all the makers to know specifically how each one does it.
Basic methods of rifling:
Button, broach cut, single point cut, ECM/EDM and hammer forging.
The method has very little to do with the shape of the rifling, conventional, 5R, rathcet or polygonal.

All barrels start out by being drilled then reamed/honed to size.
Honing is rare, but some are lapped at this point as well.

Button Rifled: Most common type encountered due to relatively low production costs once tooled up.
A "button" (think of it as a reverse image of when the inside of the barrel looks like) is pulled or pushed through the bore, basically forging grooves into the bore.
This is a "single pass" job, the rifling is made very quickly.

Broach Cut: very quick process to cut the grooves into the barrel rather than forging.
A broach is a long cutter with the basic shape of the grooves with many teeth.
The first teeth cut very little while the last teeth cut the final dimension.
All the teeth in between are cutting progressively more metal.
This is a single pass process as well.
Pushing/pulling the broach through the bore causes a completed barrel blank to be created.
Olympic barrels are broach cut as are many pistol barrels.

Single Point Cut: a slow process or removing a very small amount of metal with dozens to hundreds of passes down the bore.
Advantages of single point cut are the ability to make almost any land shape and groove diameter without making special broaches and buttons.
Disadvantages are that this process is very time consuming therefore expensive.

ECM/EDM: this is an electrical discharge or arc method of removing metal.
An electrode with the shape of the grooves is slowly pushed down the bore while electrical current causes the metal to burn away the metal in it's way.
The whole process happens submerged in a liquid.
This process is capable of very smooth finish in the grooves.
This is commonly used on handgun barrels.

Hammer Forging: this is the most radical method of forming a barrel.
Take a mandrel that's the reverse image of the rifling and slide it down the bore.
Now the hamer forging machine literally beats the shit out of the OUTSIDE of the barrel blank until it is squeezed (forged) down onto the mandrel.
Lastly, remove the mandrel and the bore is done.
Ruger barrels are hammer forged.

There are likely other processes that I either forgot (yeah, that's the ticket) or am not aware of.
We shall wait for Gunzilla to bring us up to speed on those

Each process has it's distinct advantages and disadvantages such as initial setup costs, expediancy, per-piece costs, caliber change-over costs, length limitations, dimensional accuracy etc...

Quoted: Randall, what do you think of polygonal rifling? It seems people either hate it or live by it with no inbetween.

I won't pick a side on polygonal vs conventional due to my lack of first hand experience.
I have only made 1 barrel with polygonal rifling and the guy that bought it told me it was shooting 3/8 moa groups.
Now for some reference, this was a Lothar Walther 1:10 twist stainless blank that I made a supersonic only 300x221 barrel from.
I bought the blank on eBay for something like $50 as a "shot out" 30-06 sporter barrel, cut off the chamber and turned it into an AR barrel.
This was one of the very first barrels I ever did and I sold it on eBay for about $150.
I did it purely as practice and I sure did not expect the accuacy results.
I wish I had never sold that barrel because it's so accurate and has one of the few 0.625" lightweight gas blocks I ever made on it.
That was back when we still had a CNC mill at work and I could run projects on it after hours.
The good old days...

Also, how do you feel about barrel dimpling as opposed to traditional fluting? Does it offer any significant advantages and/or disadvantages?

Looks cool.
Don't think you can save as much weight with it.

Quoted: Looks good Randall... one thing for folks to think about as far as barrel quality is the rifling itself; some barrel makers take great care to make sure that 1:7 twist really is 1:7 and consistant all the way through -- it is not uncommon for "lesser" barrels to be almost a full inch off of what they claim to be... or better yet, to have what I like to call GLGGLLGLGGT rifling: Gain Lose Gain Gain Lose Lose Gain Lose Gain Gain Twist

Ywp, I have asked a bunch of makers about their twist rate tolerance.
The good ones will tell you flat out, while the others get suddenly vague with their answers.
The most common spec quoted is +/- 1/2".
The actual rate of twist is not NEARLY as important as the consistency of the twist rate.
As Gunzilla already said, some blanks will vary through the length of the barrel.
If anything you want either a gain twist, slower at the breech to faster at the muzzle or at least a consistent twist from breech to muzzle.

Here is a more detailed article on barrel making that I ran into tonight...

www.border-barrels.com/articles/bmart2.htm