I have a Benelli SBEII and want to shoot 3" 00 buckshot in it. My question is what choke tube should I use (ie.full, mod. ic )etc...I have a comp-n-choke I use to turkey hunt with, so I'm not looking to buy one. want to use the ones that came with the gun to deer hunt with

Because patterns between shotguns and chokes vary, the best way would be to get several boxes of buckshot and some targets and practice shooting at the ranges you will hunt at and see what choke patterns the best.

As a general rule, larger shot needs less choke than small shot, so I'd start with IC and go from there. Pattern testing is the only way to know for sure.

Bye
Jack