Modification of a Schneider Xenon 16mm 1.9

[LyleBright]

An unusual problem. I shoot this lens on a micro 4/3rds body. The lens vignettes to a degree and this is logical since it is a wide lens for the micro 4/3rds system.

I am contemplating grinding off the portion that you can see here that is black. It will not stop all vignetting but (I hope) will reduce it.

My first question is: please note that on the silver ring, just where I put the yellow circle, there is a screw, and there are 3 such screws on this ring. I assume that if I unscrew the screws that this ring can be removed so that I can then grind down the part of the lens that creates a large part of the vignette.

However, I am uncertain what may happen if I loosen those screws!

That is all I need to do: remove the f stop control ring; grind down the protruding part, and reassemble.

Any advice here (this must be very simple) would be appreciated.