You can buy a Remington 870 Express for about the same amount of money, or even less for a used gun, and you will have a better shotgun.
I like the Mossberg 500s, don't get me wrong, but inside the trigger group there is a bakelite "tit" that holds the action in place. Firing repeated magnum shells can break that tit off, and then the gun will not lock up, and MIGHT slam-fire on closing. Your new part will cost you about eighty bucks plus gunsmith time. I paid my tuition to learn this lesson.
So if I am counting on a back-country gun, it would be an 870, and millions of hunters and shooters would agree with me.
Doug