ORIGINAL: ReDoT
first of all and MOST IMPORTANTLY, you need to find out what twist rate your barrel is. Rem. barrels are usually a 1:28 twist where as Hastings barrels are a 1:34 twist. If your twist is under 1:28, forget about the high speed, light bullet slugs, they simpley will not stabalize and will shoot all over the place. i know slugs like the core lokts and hornadys SST's look pretty, but if you dont have the proper twist rate, dont waste your $$$. On my setup, the bore size hastings and rem. buckhammer slugs shoot best with the attached sabot tail. with a red dot sight i can shoot 2" groups @ 50yds all day. also, worth a mention are the brenneke golds, they have shot well out of anyslug gun for me.
I think the twist on the 20 gauge is 1:24. I was shooting the 260 gr. core lokt. I am gonna try the 5/8 oz. barnes expanders later this week. After shooting 15 rounds through the barrel is was remarkably clean. Not sure what that means but I do not think that copper fouling played into it. The boys at cabelas said the the sabots will give me the best accuracy and to try and stick with them.
Lastley, can you adjust the trigger on the 11-87. I appears to be set at around 6-7 pounds.