Mossberg has been including a wooden dowel with 2 o-rings for more than 20 years.
I thought all the makers inluded one.... was your remmy in the box? Being an HD maybe the dealer or Reminton just didn't plan for it to in a field during migratory bird season... It don't matter what you are after... it is real hard to talk yer way out of a game fine during M.B. seasons if you are caught with an unplugged gun.
I was out shooting jugs in my wooded backyard in 1989 and a G-DUBYA pulled in and wanted to see my plug... I told him "DUDE..." (I was 21 then...) I ain't seen that thing since I chucked it in the trash. Mind you I am holding a HD 18 inch 20 gauge with PGO grip... Like I was shooting doves by busting off 100 rounds an hour between beers I by myself and my dogs...
Brent