It would have been a Marlin factory part. If they were subbed out whoever made them wasn’t marketing them under any other label. Quite frankly they are junk compared to the old Lyman offerings.
These are what you’re missing. Maybe look in the end of your case if you say it was missing when you pulled it out, they’ve been known to pop off if they get a little twisted or tweaked.
https://www.gunpartscorp.com/products/407670Phttps://www.gunpartscorp.com/products/407640A
