Same here. Even after a good cleaning now my sbe cycles sluggish. This happened right after I started using the Nitro Pheasant. Hmmm
I have noticed that once heavy recoiling rounds start going through benelli inertia guns the recoil spring wears quickly. Get a wolff +25% spring for your SBE. They are 12 bucks and they are well worth the money. Ive seen this problem happen a lot on the duck hunting forum I am on where everyone is shooting 1500fps 3" shells or bigger.
I have personally shot Nitro Pheasant #5's for the last 4 years and loved them. Before that it was Winchester supreme #5's