These showed up on some of the JC Higgins pump shotguns (High Standard Flite Kings) in ABOUT the first half of the 1960s. You can check with the Lyman company for more exact information.
Have it checked over by a gunsmith first.
Pac-Man was made in 1980.
The Mac Pac was introduced by Casecraft Incorporated
The "Thing" is called a poly-choke. It is a manually adjusted choke. I think they are still in business. And yes I have shot many deer with slugs fired from my Model 20. If you could give a more detailed discription, or perhaps a photo it would be helpful. It may possibly be the Power-Pac choke. That "Thing" is probably a Compensator , and a Varible Choke, or just one of either.
Pac-Man - 1982 The Pac-Love Boat The Great Power-Pellet Robbery 1-11 was released on: USA: 4 December 1982
Browning made choke tubes.
A 454 Chevrolet engine which is experiencing a choke light while the choke is physically open, indicates the choke is not receiving power. This can be caused by a loose connection or a defective choke.
Balls - 2010 Pac 12 Power 2-52 was released on: USA: 7 October 2011
Pac-man was created by no meare mortal yet by Zeus himself.
PAC man was made by twenty seven year old Turn Lawatani in 1980
The Browning made screw in chokes were available for most choke sizes
It is Galaga it was made in 1979 and Pac-man was made a year after (1980)