Problem you describe could be any one of several things. One of the harder ones to detect is when the trigger assy. is out of the gun, if someone released the hammer/pulled the trigger w/o restraining its movement and let the hammer slam into the carrier latch. If you look closely, you will notice the front of the carrier latch has a very small metal tab on it. The angle of that tab is critical for proper functioning and if the hammer has been allowed to slam into it, it is likely no longer in proper orientation. It does not lend itself to being bent/returned to its original angle, so will need to be replaced, if that's the issue.
Another item to be aware of is that early 1100's had an aluminum piece between the return spring and the fork. They can and will ultimately become bent causing undue friction inside the return spring tube and in worse cases cause what you are describing. Remington was aware of the problem and went to a steel piece that eliminates that problem/possibility. Check yours and if it is aluminum toss it and get a steel one. While you are doing that clean the inside of the return spring tube like you would a gun barrel getting all the junk out and leave it dry afterwards. Also check the free length of the return spring. If it is 14" or under, replace it. FWIW, Remington has had the best prices on that part in the past.
Also do the same thorough inside cleaning of the magazine tube. Some people replace the follower w/a red or orange plastic one for reduced friction as well as it serving as a visual indicator there are no rounds left in the magazine. A lot of junk & grunge can accumulate in magazine tubes and it too can cause feeding issues when it isn't clean.
Next, the interrupter that is held to the inside of the action with a snap ring can become worn to the extent it wobbles and causes feed problems. Remington sells those snap rings in several thicknesses to take up the slop so the pivoting action is once more tight, eliminating the side to side play. If the gun is to be used for skeet or games where only two shots are necessary, the interrupter may be removed altogether as it is only really necessary for the third shot & beyond.
And one other very important thing is to be sure that you have the piston & ring properly oriented between the action bar and the 0-ring on the magazine tube. Might wanna double check that first. Its easy to get them on wrong, if you are not familiar with their orientation.
Lastly, check that the gas vent holes in the barrel are not sooted-up/constricted w/carbon. You may use a number drill very carefully by hand only [you do not want to enlarge the hole size(s)] or a pipe cleaner soaked w/a good solvent.
Hope something here is of use to you. Let us know how it turns out.
