MissileCop I have a Rem 11-87 with a 20.5" barrel and I went with a Tac-Star 3 round extension. It doesn't stick out past the barrel and it hasn't broke yet. Actually it is rather well made. It give me 8 (7 in the tube 1 in the chamber) in the gun and 6 in a sidesaddle.
Damn my gun gets heavier every time I get a new catalog. My next purchase will be the new Surefire forearm with integeral (sic) flashlight.