[skeet]

The 3 inch bbl will fit and function on the 2 3/4" gun just fine. What it will do however is beat the gun up pretty badly(if you shoot 3" shells in it regularly). The differences in the 2 are minimal but still different. The piston is heavier and there is a different buffer in the bolt and a few other little things. The preferred way to trade bbls on a 1100 is to have a 3" gun and trade 2 3/4" bbls onto that receiver. Work fine and no problems with beating up the frame. 1100 bbls are also getting a bit more expensive now days. Any decent barrel on ebay brings over 100 bucks(ribbed). Just bought a super rare 34" Trap bbl for one today. It'll bring a premium on ebay. I also have a 2 3/4" 20 ga 1100(Standard weight) that I use a 3" bbl on but I did do some conversion to the piston etc so I can do it. Love those 1100's. Also bought a 1 of 3000 Commemorative 1100 with all the pretty stuff on it today. Think I'm crazy!!