Anyone ever see this before? Gun was leaning against the kitchen table in a padded soft case when it was knocked over and decided to break into pieces....
Doesn't much matter, but on mossbergs that tube is heavy duty and was most likely damaged prior to the spill, that should never have happened as described.
I have a better picture now that I have it apart. I sent it to a friend that owns a gunsmithing business. He thinks that there had to be a defect in the tube. The gun has less than 1000 rounds through it and has never been abused.
BTW, I have not heard back from Mossberg about the matter. With the holidays I am betting it will take awhile.
Just FWIW, the mainspring in any gun is the one that drives the hammer or firing pin to fire the cartridge. That spring is called different things by different makers, but usually the action spring, and the tube is the action spring tube.