RE: 3 or 3 1/2???
If you are shooting at 35 yds a good 3 in shell will do the job. I have a Mossberg 835 but I'm thinking about selling it, my problem is the at 5' 7'' I have short arms so I grab the forearm at the end of it. The balance is all off and last year a couple of times my gloves jammed forearm when I pumped it.