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??