Are ER Shaw AR15 barrels any good?
Looking at the Varmint/Bull 1/8 twist 5.56nato chamber barrel profile for my newest build.

ER Shaw makes barrels for a number of companies including Colt.  They seem to know what they are doing.  Just keep in mind that they make barrels to the specs set by their clients.  I've seen some dealers use the ER Shaw/Colt connection as marketing to advertise their own barrels.  Just because the barrel is from ER Shaw doesn't mean you're getting a Colt barrel.

+1

Quoted: ER Shaw makes barrels for a number of companies including Colt.

Model 1 Sales too.

IMHO, if you are going to spend the $$ on a new barrel like that, why not get a high grade custom barrel?

Shaw barrels are about all I use myself, I have always had good service out of Shaw products

Shaw barrels are funny in the fact that their consistancy is never really on.  Sometimes you'll get one that will shoot like a dream and other times...  well...  

Not only have I barreled quite a few actions with ER Shaw's work, I've visited the factory and seen their production techniques.  I can tell you that their work is geared towards production production production.  Don't get me wrong, they do an AMAZING job at churning out a massive amount of barrels and selling them at a great cost.  Not only that but you might be surprised just how many guns in the US are sporting Shaw's work.  My suggestion to you is to use Shaw if you're building a plinker, or if you intend to hand-lap the barrel yourself.  If you're trying to build a tack-driver then just drop the extra money on a premium barrel.