The two differences between a 2 3/4" and 3" chambered barrel are:
1. Obviously the chamber length
2. Number of gas ports in the barrel. The 3" only has one gas port, while the 2 3/4" has two. Note that the holes are not the same size in both.
With regard to the steel not cycling as well, make sure your 1100 is spotless clean before hunting with it. Remove the barrel and ensure the gas ports are clear of any dirt and powder residue for flawless functioning. As well, lightly polish the magazine tube with solvent and 0000 steel wool and lubricate sparingly. Check the gas rings for wear and damage, and clean them as well. You can drop the trigger group out easily and spray it down with solvent and lightly blow all the crud out of it. Clean the inside of the receiver with solvent and a toothbrush. There is a good picture in the manual on the lube points for the trigger group on the Remington website.
If all this is done, and it still does not cycle correctly, then you probably have a mechanical problem with the action.
I would urge caution if you decide to go with the enlarging the ports route. If done incorrectly this can give you heavy recoil on the receiver and lead to a possible early failure of the action bars.
God luck.