I suggest you go to Shotgun World and go to the Remington section and at the top there is a good thread on properly cleaning an 1100. I give mine a 5 minute swipe anytime I shoot one of them, but once a year it needs a thorough cleaning, including the gas ports and the action spring in the buttstock.
If an 1100 is jamming something is wrong, either with the gun or the owner.
Is yours a Magnum model? If so, 3" 1100s usually need fairly stout 3" steel loads to work properly. A 2-3/4" Model 1100 should have no problems with any normal 2-3/4" load.