Wow, just found this. The title seems a little deceiving since the content is more about general barrel performance as opposed to CCI muzzle breaks only. Title change?
To backup what The shootist said with what I remember of punkworks tests circa 2009.
I'll update if there are any inaccuracies.
Punkworksr results as I remember them:
Ideal bore length: 8-10 inches
Ideal porting length: 2-4 inches
Ideal total barrel length: 10-14 inches
Ideal overbore match: +0.005 from "just slips through" paint test everyone uses
(Ex: .684 paintball size, .689 overbore is ideal)
Ideal underbore match: -0.005 from "just slips through" paint test
(Ex: .684 paintball size, .679 underbore is ideal)
Danger zone underbore: -0.010 from "just slips through" test
(Ex: .684 paintball size, .674 will likely start popping paint)
Performance of best vs worst barrels: very small performance difference
Biggest observed performance difference: barrels with sharp edges or defects on the inside
I don't think they ever talked about minimum bore length.
My own observations:
This might also explain why CCI barrels and long underbore barrels (like a .678 lurker barrel) that are 8-10" before porting shoot so well.
Looking at the few barrels I have (CCI 8" with muzzle break, J&J 12" 2-piece, Proto 2- piece 14", CP 12" one piece, Gog eNMEy stock 10" one piece), it looks like most of them start porting before the barrel reaches that 8"minimum. Adding a TechT iFit kit adds another 1 3/4 inches which pushes most of the barrel backs into the 8-10 threshold. So the iFit might have that added bonus of additional non - ported barrel length along with low bore sizing for ball retention. Maybe not the perfect solution, but not bad for a quick and simple adjustment to existing equipment.
Last edited by Bang*Bang**; 02-05-2017 at 05:00 AM.