I have a brown Pachmayr Decelerator slip-on size L on mine. Fits pretty good and doesn't look very bad.
Shot 3-4 boxes of 3" magnum slugs (Remingtons & Federals) the other day without any ill effects on the shoulder...
The pad slipped out half the way though on one of the shots...
BTW Remington Slugger 1 oz (not the hi-velocity ones) seem to group best out of mine - the right barrel shoots ~5" to the right, the left barrel ~5" down. This was @25m, don't ask what happened @50m...I wouldn't try any shot with slugs @ more than 25m unless I keep track which barrel the slug is in and try to compensate...and I don't think even this will work...