What was the purpose of the circular ring on “old” cannons right before the muzzle

Question

I’m guessing it’s for structural reinforcement, but not all cannons seem to have it, and I’m having difficulty understanding how making a small ring which seems to be less than a cm thick extra would make enough of a difference to warrant adding it. Also, does it have a name?

EDIT: Image: https://imgur.com/5oGdoAm

In: Engineering

Answer 1

It is likely a muzzle brake that redirects part of the propellant backwards to reduce recoil.

Search for an image of “muzzle brake cannon” and look it that is what you were asking about. If not reply with an image of what you refer to if that is not the case.