My full sized RSK behaves differently to the mini. On my mini, the locking button doesn't make much difference. I have adjusted the pivot screw so that it will open with the thumb stud on the blade, but slightly stiffly. It won't open by gravity or by flicking, regardless of the position of the locking button. The smaller blade doesn't have enough weight to overcome the stiff pivot.

This is how I like it. I tried making the pivot very lose, which got rid of the stiffness and made it a smooth joy to open, but also meant it could partially open with a flick. I was worried it would open when I didn't expect or want it to.

My full sized RSK is also currently adjusted so it will open with the thumb stud alone. It won't open by gravity or flicking with the locking button up, but on experimenting I find I can sometimes shake it half-open if I hold the lock down. The first time it flicked completely open and locked, which surprised the bejeesus out of me. [Later...] and now I find it will partially open, even with lock up, if I strike the end hard against the palm of my other hand.

I find this a bit disconcerting. I had already decided I'd never toss either knife to someone, and now I'm thinking that is definitely wise. There's a real chance it will open spontaneously. On the other hand, I am pretty confident that neither knife would be considered a flick knife or gravity knife, or "made for causing injury" under the UK 1953 act, because opening it in these ways is so awkward.