Good choice! An M500 20ga deerslayer will get the job done..
I have an M500 in 12ga.. Because of additions I have made to it, a full teardown for cleaning has become troublesome, and will ruin the zero of the sights.. So I use a boresnake for the barrel, and Birchwood/Casey Gunscrubber solvent/lubricant in aerosol cans, for inside the action.. Shotgun shells are pretty dirty, leave a lot of powder residue!
It works good.. But just know, this is the lazy mans way of cleaning your weapon, and is generally frowned upon.. A REAL cleaning, requires that you fieldstrip the barrel and action! You SHOULD learn the feildstrip procedure for your chosen weapon, it IS an element of firearms competence!
Good luck and happy hunting,