Originally Posted by
Kuromori
It's just a lowly BSA lockring. It's not even the BB cup. It's hardly the end of the world if it gets a bit marred, or a couple notches get screwed up. It's not some irreplaceable piece of history or like it would get damaged beyond the point of usability. It's not even in a highly visible place.
Given the internal fillets and what appears to be a 1.37 marking on the cup, it's almost certainly BSA.
Maybe so, not the point, there's value in learning the drill for when it is a valuable specimen that you do want to save with the least amount of damage that doesn't cooperate.
This can make good practice when the stakes are low to acquire the tools, learn to use them and get it right.