I recently picked up a "select" .308 barrel for a build, made by black hole weaponry supposedly. Their site usually lists what blank they use, or if you search around you'll find out what manufactures/machine shops are doing the work for them. All of the reviews i've read where match ammo was used have been positive.
The select polygonal looks great, should be seeing how it shoots this weekend. Was looking for lightweight and it's got a nice profile.