Tight B60 Step Up Ring

[p956lh]

I've got a 100 CF and I have a problem trying to fit a (brass) Kiron-made B60 to 67 step-up ring onto the lens' B60 inner thread. It's tight, I haven't managed to screw it in yet.

A previous Fotodiox aluminium step-up ring also couldn't fit.

Is it normal for it to be this tight? Which way am I supposed to turn the ring, clockwise or counterclockwise?

Thanks.