YOU PROBABLY HAVE A WORN OR DAMAGED O RING ,
YOU NEED TO REPLACE THE RING AND UPON PUTING IT BACK TOGETHER
DO NOT RELEASE BOLT BY SELF YOU NEED TO MANUALLY WORK IT SLOWLY BACK AND FORTH IN ORDER NOT TO DAMAGE NEW RING.
ANOTHER PROBLEM COULD BE YOUR GUN NEEDS TO BE CLEANED AND LUBED.
ANOTHER PROBLEM COULD BE THE CARTRAGE EJECTOR GRABBER COULD BE WARN.
TWO SPARE PARTS TO CARRY IN THE FIELD, O RING & CTG. CRABBER FOR SHELL EJECTION.
my dad bought me a 11-87 and it works great but it wont eject the low base shells and thats fine cuz i only would shoot them for trap but then it started not ejecting the plain old 3" mags so i just spray all my shells down with silicone spray and now it ejects like butter