Does anyone know where I can get a barrel in this caliber.  I know it is a wildcat cartridge but want to give it a try.  I would prefer a carbine length barrel to swap onto my M-4  Thanks  Dennis

Olympic Arms has 6x45 barrels... 20" for sure, don't know about 16"... check olyarms.com.  I have an Oly SUM 6mm PPC barrel... seriously accurate.  Also check ar15barrels.com, although not listed on his website, he will make 6x45 barrels.

Have you considered the .300 whisper?  Barrels are availble everywhere (even Model1 has them), and you can make the brass easily from .223.  I think that would be a cool caliber to play around with since you obviously reload.  

Scot

I wanted the 6MM or the 7MM and went with the .300/.221 or what they call the 300 fireball, JD likes to call it the .300 Whisper.

Got it from Model 1 Sales and as always they were fast and I got just what I ordered. I have no regrets not getting the 6/7MM. Used my 30-30 dies to form the brass and was shooting it in a couple of hours. Best load so far are 150 grain SP. I've only shot a few 168 grain, very easy shooter.

IIRC Kurt's Kustom makes barrels in both 6x45 and 6.5x45.  Check with Kurt in the Industry section.