Call Rob or Jonathon @ Gobbler Guns 877-251-9955 and tell them what shell you are shooting and out of which gun and see if they will send you a choke.....now they did it for me,but I'm not sure ifn they do it anymore. They sent me a .660...negative ,then they sent me a .655....it was really good but I thought it could be better so they sent me a .650...$$$$MONEY$$$$ ....so I sent the other 2 back ,THEN PAID THEM,and got a damm fine set-up...they also lengthened & polished forcing cone in my gun. Benelli SBE2 24" bbl. H-13 3.5"-2.25oz.-#7 .....336 in a 10" circle @ 40yds. Proof is in the puddin' gentlemen. Hollar at me ifn you wanna see that target,I cant figure out how to upload it...