Hi Guys! What's on the end of my barrel?

[grandpa870]

Just inherited a Wingmaster 870 and trying to learn more about it. From learning about the date codes, it was manufactured in February of 1973. It has a 26" vented rib barrel with a mysterious device on the muzzle end. It's externally threaded, larger than the barrel. It's solid, not ported or anything like a muzzle brake.
Is it original? An add on?

[BKinzey]

Never seen something like that.

Did a Google Lens search and amongst the pics of scopes there was this on another shotgun brand:

https://www.easyliveauction.com/catalogue/lot/7d80d5027b48ca2e45f5df0ff37ca9f8/0af8d24542e81eb9357e7ef448a6646f/sporting-country-pursuits-auction/

They called it a choke. Doesn't look like it "chokes" anything to me.

Choke.jpg (63.75 KiB) Viewed 4012 times

[Scorpion8]

OP's original pic looks like an old SMLE dust suppressor for the jungles. Diffuser of some sort? An inside pic would be needed.