Call the folks at Rhino Gun Cases in Williston, Florida. (800)-226-3613. Ask them what constriction they recommend for your gun. I ordered a choke for my Beretta 391 and it performs like a champ. They told me the .660 choke would shoot both Hevi-Shot and lead equally well, and it does. The patterns with Hevi-Shot are particularly spectacular, almost 90% at 50 yards in a 30" circle!!

Good luck. You won't be sorry

Tyler