Make sure the magazine tube is clean and LIGHTLY oiled. The gun recoils to eject the shell and if this tube is dirty it slows down the recoil too much. You also must hold the gun tight to your shoulder, if not the energy is not transferred to the barrel but just moves the entire gun. Extremely light target loads may not provide enough recoil to operate the gun. Also make sure your chamber is free from rust and dirt or the shell may want to stick and not pull out.

 

It could be that the ejector fingers arent catching which they might just need cleaned or theres somthin in it so it dosent grab or it might be loose just from use which i would just say bend it back or find a replacement

 

chances are its short cycling on you. Is it a 3 inch chamber and your shooting 2 3/4 shells? 3 in guns have only 1 port while 2 3/4 have 2. Check the gas o ring, make sure its intact. Gas system in correct order? I see many people not putting them back correctly.
Extractor tension can be a problem but not as common as a short cycling gun.

 

11-48 was 2 and 3/4 inch Only. The extractor does not so much pull the shell out of the chamber as it does hold it while the barrel goes forward. If it were to go bad the gun would trying to feed an additional round as well as failing to extract. When the barrels slams forward the ejector on the tail end of the barrel pops the shell loose and out of the gun.