Wetpowder,
As old as this post is you may have it figured out by now, becauce a few guys already told you "what's up"(Kelbro's post).
As men we sometimes don't need to read directions, but I'm sure somewhere in the manual it talks about using larger loads to "break-in" the action so that your gun can cycle lite loads.
When I first got my Extrema I ran 10 rounds of 3 1/2 inch turkey loads through it as I was pattering it for the season.
I then ran two boxes of 7 1/2 inch high brass through it on the skeet range.
I can now shoot 7/8 oz Wal-mart Federals through it with no problems.
Before you tell me I'm shooting a "gas gun" and the Benelli's are "inertia driven"; try it.