ARe you checking the GPM at a hose bibb? Sounds like you are. 6.6 is okay for the hosebibb. If you tap directly into the 3/4 copper you should get 11-14 GPM I would think at 60psi.....just a guess not scientific.
If you do the bucket test at a hosebibb, lots of times the hosebibb is very restrictive, usually it is 1/2 " copper.
Sprinkler Solutions, Inc.
Arizona and Colorado
www.sprinklersolutions.net
Sprinkler Solutions, Inc.
Arizona and Colorado
www.sprinklersolutions.net