I think you are going at it backwards. Instead of THINKING that the chokes have to be thus and such to utilize slugs and buckshot, you should be customizing them to do so. Begin where you are (and probably with Breneke) to see how it performs. It may be harder to get it to pattern buckshot than to regulate with slugs. The late Ralph Walker, in his book, "Shotgun Gunsmithing," describes getting shotguns to pattern well with buckshot. It was a matter of cut and try until performance was optimized. He recommended against OOO buck as he never could get it to pattern in any gun. Let someone do this kind of work for you or use rotary stones yourself on the last parallel section of the choke only, then shoot for pattern. It is not as hard as you might think. Do not lengthen forcing cones at the chamber unless you want the slug impact to drop a good 6 inches. Ask me how I know...Remember that the performance gained will be for THAT load, only. Change any variable and all bets are off! Good luck--Steve
P.S. Are you sure you wouldn't rather have a large caliber rifle insert for the purpose described?
