Originally posted by K David the non system-lenses that I have don't affix tightly enough that I would want to carry them around town on a walk or the like. Now, if I had a Dremel, I could put a small divot in, at least, the Olympus lenses and get the Pentax pin to lock into place.
My Olympus and C/Y lenses fit firmly, but the one Nikon lens I have (a pre-AI 105/2.5) does tend to slip when I try to turn its stiff aperture ring. The Adaptist kit includes special plastic spacers for Nikon lenses that help hold them in place, but they seem to loosen after a while.
Another little problem I forgot to mention before: If you leave Olympus and Nikon lenses on the camera for long, the three leaf springs behind the camera's mount ring will lose tension, and Pentax lenses will then fit a little loosely. The springs can be retensioned, but it requires removing the mount to get to them. I wouldn't want to do that too often, either, as it might fatigue the springs.