Shotgun is the M3-S90, pre-ban model with full length magazine tube, I bought a couple months back. I bought another shotgun before that too but this is the only one I've shot so far. I remember you have a M1-S90, right vooduchikn? Does yours cycle birdshot? Mine cycled some birdshot fired from the shoulder, but not from under the arm. The M1 and M3 aren't really supposed to cycle birdshot from what I hear, but some people say theirs does and some people say theirs doesn't. Anyway with the M3 I can just switch to manual pump if I have to.
Also, do you have any issues with loading your M1? When I insert cartridges into the magazine tube, my thumb often gets stuck in the tiny space in front of the carrier and is hard to get out.