I found that a long double offset has a lot of mass, and needs more pressure than you'd think. There were places where I had to use it, but I tried to find other ways whenever I could. I don't remember specifically how much pressure I had to use, but the exact number would vary depending on the gun and other factors anyway. Don't be afraid to crank it up to get the result you need.
RV-12 # 222 N980KM "Screamin' Canary" (bought flying)
Fisher Celebrity (under construction)
Previous RV-7 project (sold)