filed that area off ? it will ruin the nice look of the adapter, but what else I can do..
I have been using it with collapsible 50mm f2 CZJ, it can be collapsed on IIIC/M2/H-RF and RD1 safely, BUT, there is a small problem which is the claw of the collapsible lens is big enough(or the diameter of the collapsing tube is bigger) than normal elmar/cron/industar which may hit the RF focus wheel internally.
so in order to collapse it safely, I need to push slowly and turn somehow to make the focus wheel doesn't hit by claw.
when the lens is fully in, any attemps to turn the lens will make the claw rotate and hit the RF wheel, no problem as long as you don't do it often and with force, or else the RF wheel may get damaged/or calibration issue will be exist.
keep it small & simple :
M2-T BP, IIIc-T BP ST, H-RF, RD1, BII C-Heliar,
T is Titanium !!