That seems to be the main difference between FED lenses and Industar-22's.
Well, I believe both weren´t designed for the FED2... the FED-Industars and KMZ-Industars were meant for the LeicaII-Copies like a FED1 or a Zorkii1, not the later FEDs.
On some (but not all) of the Industar lenses the focusing tab hits the camera front just before infinity focus. I'm tempted to grind them down a bit...
With grinding it down you´ll probably losen the tab.
Ole, may I suggest something else? Your lens is a KMZ-Industar22, whats the production year?
I have a I22 from the early 1970s here - a friend bought that for his Bessa R, got stuck with a problem and gave it to me as a gift. The problem? A nerd cut of the Tab which now allows mounting it to later FEDs but leaving it without a mechanical stop from unscrewing it.
What about exchanging the two parts - you get the "FEDed" ring, I get a functional one and we both can use it with our cameras... It seems to weight less that 20g which would allow me to send mine via "Europabrief" - a letter. Everything else would be prohibitive in terms of shipping costs.