shane019 wrote:I wouldn't think it would be the spring if it works fine with 3 inch and not 3 1/2" because there is more gas to operate the action out of a 3 1/2".
Have you cleaned your gas ports?
Tried different ammo? I know I had a bad batch of ammo one time that would jam 3 different guns.
I 2nd this. I've had this problem happen on occasion usually I've had the problem when shooting shells that are dirty from riding around in dirty blind bags or hunting vest. I'd clean the magazine tube really well it seems to get gritty and not get the next shell pushed into the receiver quick enough. Those longer shells have to travel further in the same amount of time as a 3" shell to load correctly. Might be worth a try.