CP barrels are great, if you use the tactical versions they have a consistent outer diameter (I think 7/8 or 1 inch, a google search will solve that)
I think you can still find some Tiller, J&J, and Smart Parts 20 inch barrels out there still. Those "flute sniper" barrels with no manufacture are normally from China and are knockoffs, probably not worth your time.
+14 years of paintball experience.
Loves double chocolate cookies.