I have a Mossberg 500 muzzleloader barrel. I so wish H&R would have just followed their lead. The breechplug isn't removable nor does it need to be. It's cleaned just like an old timey muzzleloader from the muzzle. You just open the breech, insert 209 primer, close the breech, and fire. I really want a single shot blackpowder shotgun but I don't want to pay an arm & a leg for it.
So what do you do after 200-300 shots and your flash hole is eroded? Throw it away and buy another?
The breech plug is replacable, and therefore renewable. I have some custom breech plugs with a removable vent liner that should last about forever. I like removable breech plugs, they allow you to customize your ignition and replace your worn out flash hole. Just my 2 cents.