I usually do my homework before I buy a gun to make sure it's not a POS. Before my last purchase I really didn't have a "worst" gun. I guess the least "needed" was probably an old S&W Model 10. Even though it was probably the least "needed" I wouldn't get rid of it.
I just recently bought a Mossberg synthetic stock 930 combo, my first semi-auto shotgun and first Mossberg. I bought it because it cost $550 brand new and came with two barrels, and I always wanted a semi-auto shotgun. Mossberg seemed to have a reputable name and the reviews were mostly positive.
The trigger group wobbles linearly in the receiver, ok, as long as it functions properly, I can live with that.
Upon fully loading the mag tube with four 2 3/4" or 3" shells, charging the bolt does not release the round from the mag tube and the bolt either locks back or doesn't, randomly. With 3 rounds loaded it will release a round randomly and it works pretty consistently with 2 or less rounds in the tube.
I haven't even shot this gun yet. What I have discovered is that the shell stop "arm" foot is too long and extends a good ways onto the base of the shell, with a fully loaded mag tube, the increased spring pressure is enough to keep the shell stop arm from sliding off the rim of the shell and releasing it. With fewer shells loaded, hence less spring pressure, the shell stop arm is able to move completely out of the way releasing a shell.
I have contacted Mossberg early last week and have yet to hear back from them, but as of right now, this is my least favorite firearm.