the choke says .655 and i am shooting a 12 ga benelli nova 28" barrel. i am going to try and get some large pieces of paper and get a chance to see the whole pattern. i might be off and just missing the good section of the pattern. ive got federals remington and some winchester all in 3" and 3.5" number 6s and well see what i get. i might try to post some pics and will definitely let you guys know what i find out. thanks for the help.