My advise is, take atleast 2 guns in good condition and get yourself a limb saver recoil pad that you can move from one gun to the other. Might sound sort of "sissie like" to use the pad but you will be glad that you did.
Another handy item is "slightly" yellow glasses, they will filter out the UV stuff and also seems to "clear" emages up, a little.
That 870 will do just fine, probaly better than most semi autos. However, be sure that all of the moving parts are in "excellent" condition.
Have a great time, we are all invious.