Hey rick I have a new mossberg 535. What I have is a improved cylinder choke, I use Remington slugs, which will give 2-3 inch patterins at 50 yards. But at 100 yards I get 6-8 inch patterns or so. I don't think you can get 4-5 inch patterns at 100 yards, unless you are lucky. The really way to get true accuracy at 100 yards, 150, and 200 yards, is to buy a H&R ultra slugger. At 100 yards can get 1 inch patterns, at 150 yards you can get 4 inch patterns, and at 200 yards you can get 6 inch patterns. That is what I am buying this summer for about 400.00 dollars or so. That is what I would do if you have the money. if you have more questions about H&R's go to the H&R forum.
Hope I helped
Buckshooter