Benelli Sport II 20 gauge feed problem

I bought my wife a Benelli Sport II 20 gauge at her request to shoot with me, she would shoot fine for about 75 rounds then it would start to hang up on the second shot, not always but somewhat intermitent. I could take the gun from her load it up and shoot 10 -20 rounds and it would cycle fine. I figured she was getting tired and soft shouldering it. We continued to get her mount tuned in and the problem continued for her to the point I went out and bought her the new A-400 20 gauge. One issue cured, and now she knows why I need all these guns!!

Now I am trying to get this gun to operate correctly. It is starting to jam on the second shot for me now so I know it is more than just the operator. I have ruled out it being a cleaning issue (Mutiple times). The gun has about 1200 rounds through it so it is broken in. I bought it used with about 600 rounds through it. There is no consistancy in how it jams, sometimes it will eject and not close completly, sometimes it won't eject at all, 80% of the time it works fine. The only thing I have noticed is when I manualy slow cycle the bolt it will not turn the bolt into the lock position. If I pull the bolt back a 1/4" or less and release it it will rotate in place fine. (Seamed odd to me knowing the bolt design. The locking lug area is clean....) (Ok saw on Benilli web site this is how it should work so thats not a issue.)

The only place I have not checked out is the return spring in the stock, will get in there tonight. Anyone have any Ideas??? See below....

Ok Pulled off the stock, cleaned the inside of the recoil tube, spring and wiped down the recoil plunger. It was not all that dirty, only slightly so, but with a good wet oil coating. I cleand it dry and then used Hornady dry lube prior to reassembly. Took the gun to the sporting clays course the next day. 30 rounds without the gun missing a beat (Me either) then it started to hang up loading the second shot. I pushed it through two more stations with it continuing to get worst, by the third station I went through 5 pairs of birds with it not feeding the second round. Finished that station with someone elses gun, then went swap out guns.... I am at a loss....

 

With reloads or all new shells? Also, the Benelli needs to be against the shoulder for proper function. In other words it requires resistance (Something firm during the recoil cycle) to function correctly, especially with light loads.

Make sure the gun is firmly against the shoulder when firing.

Powder residue could be building up as well and slowing the action. Have you tried other shells?