I have seen it before in Mossies. It isn't 'normal' in that it shouldn't be there, IMHO it is slipshod QC (quality control) on the assembly line. What you do about it is up to you. You can let the factory deal with it either by fixing it or giving you a different gun, or a refund.
If you want to keep the gun, you can remove the bead (it unscrews) and dress off the end of the threads slightly with a fine (swiss type) file, or other relatively fine abrasive. The trick is to keep the threaded end of the bead flat and not mess up the threads or the bead itself. There are special tools for installing/removing threaded beads that have a chuck- like device to hold the bead, anything you have with a chuck (think power drill) will do to hold the bead while you work on it. Don't use the drill to remove/install/file the bead, of course, just as a vise. Once you shorten it a fraction of a thread turn or so it should be ready to reinstall without protruding into the bore. You should not IMHO have to work on a brand new gun other than giving it a thorough cleaning, but... .
Is the Persuader the PGO (pistol grip only) M500 version? You would be happier and better served with a regular stock if that is indeed the case, IMHO.
lpl/nc (870- it's the 'real thing' among repeating shotguns)