Hi Choyin, mine is K100D (C/Y lenses with SR, so cool
). I have D25, D35/1.4, P50/1.4, P85, P135 and S180. All of them can be put on the camera. The lenses cannot be locked in the normal way as on the C/Y bodies, but they are in fact tightly fitted to the body once screwed in, especially for those lenses with the mount blades molded into one with the rear part of the lens (e.g. P135, S180 and P100 or MP100 as well). They are very secured with minimal chance of falling out from the body.
I have indeed found a solution to address the lock problem - simply drill a small hole at the rear part of the lens at the same position of the lock of Pentax and this will serve the purpose. However, by doing so means that the lenses must be damaged. Balancing the risk and the damage to the lenses, I dare not to do in this way. But sure this is a convenient solution to the issue