I came across this today. The FCR's are for pounds of feed to pound of meat, keep in mind. So 3.8 is right around a 2.5 FCR for live-weight. My last batch of Cornish X was right around 3.8 as well, so that probably means I could expect my 150 freedom rangers to be around 5.2. Good thing I raised my prices.
http://www.puyallup.wsu.edu/soilmgmt/SusAg_PasturedPoultry.htm

http://www.puyallup.wsu.edu/soilmgmt/SusAg_PasturedPoultry.htm