When you list barrel "makers" how about mentioning a little about what they make. For what actions, what twists, and what materials. And do they actually make barrels or just do contouring, threading and chambering, Here are some I'm familiar with. There are many others:
Pac-Nor is an actual barrel maker but they also do contouring and chambering. They'll chamber their barrels in 300 Whisper and they make many calibers of barrels in fast twist rates. Ive bought a couple of barrels from them for subsonic use but not in 300 Whisper. As far as I know they only do AR-15 or AR-10 as contoured blanks (no fitting of barrel extensions, head spacing, etc. It's the place Id go if doing a bolt action. They do "prefits' for many bolt and single shot actions. They offer both chrome moly and stainless in 4, 6 6.5, 7, 7.5 8, 9 and 10" twist (thats just in 30 cal)..
http://www.pac-nor.com/wildcat/
The Thompson Center custom shop makes 300 Whisper pistol and rifle barrels for the Contender. Unless they've changed recently they only make 1:10 twist Whisper barrels. CM and SS.
http://www.tcarms.com/customShop/cha...der_pistol.php
http://www.ar15barrels.com. com m aybe offers barrels if his backlog isn't too long. He gets blanks from other makers like Douglas, Shilen, Krieger, an Pac-Nor. CM and SS.
Noveski apparently makes AR-15 barrels in 300 Whisper though I don't see them on their website. I believe they use Pac-Nor barrels. If you click on AR-15 barrels on the Pac-Nor site it takes you to Noveski.
Not many barrel manufacturers make 30 caliber barrels with a faster than 1:10 twist and the Whisper name is proprietary to JDJ. A few companies sell barrels calling them 300-221 or 300 Fireball chambers
Model 1 Sales offers 300 Fireball barrels using blanks made by ER Shaw. They are 1:8 twist. M1S will do some custom contouring, gas port locations, and length made from the same blanks. The 1:8 barrels are in chrome moly only.
http://www.model1sales.com/item-deta...TOKEN=14395621
Del-ton also sells an AR-15 barrel in 300 Fireball, also 1:8 twist. CM only.
http://www.del-ton.com/AR_15_Barrel_p/cv1006.htm