Recent Model 870 shotguns have a
<u>pressed-in front bead</u>. If you're familiar with a hardware store tool called a tack puller that will pop it out for you. If you can't find one, you can make a tack puller by putting a slight upward bend in the blade of a screwdriver and then grinding or filing a V-groove in it.It will be like a mini crow bar,slide it under the bead and pop it out.
But now...how are you going to keep your new bead in??
another tip when you do pry up use a piece of a thin wood shim under the pry where the pressure will be applied to the rib or barrel,a little pentrating oil soaking prior to removal helps.don't go gorilla on it,gentle even pressure or you will dent the rib or barrel
There are these places called gunsmith shops where they have the tools to do thing correctly. I wouldn't be trying to installing a pressed on bead at home, it could just cost more than a few bucks in the long run. Just a suggestion.