It sounds to me more like the gas system. I am working on a Browning (same system) that had simular issues. Have you replaced the "O" Ring yet? If it is dried out or missing this could be your problem. The gas piston should be clean as shown and the o-ring soft and flexable. Remove it carefully and inspect it for damage.
I have had to rebuild the gas piston on these before, It takes a special tool to do so. Sometimes you can just give it a good soaking in something like brake parts cleaner (do not use carb cleaner) or a Hoppes Solvent. Let it soak overnight and then scrub it out with a tooth brush and hot soapy water. Swish it around a lot and then blow it out good with compressed air. Lube it LIGHTLY and try it again. or It might be bad.
You can get into the barrel gas ports with a pipe cleaner as Badduck mentioned or a dental pick. but soak the ports with Gun Scrubber first for about 15 min then try to clean them out. The canned air with the plastic tube for cleaning computers works great for blowing them out.
just curious but is this a 24" Model?