I have a hard time believing these pins shear when shooting factory ammo. I know guys that start at max in the reloading manual and work up from there, stopping when they have to pound their bolt open with their boot heal and a primer falls in the magazine well. Usually the bolt handle breaks off or rotates on the body(M70).
But maybe the 100's are bad. Time will tell, but a non shooting attorney should be aware and acknowledge that owner abuse can cause such problems before crucifying Mossberg.
dan