Thanks, that's useful to know about the advanced bind menu.
I did some more testing and found that I can bind X to mines and C to grenades, and they will work reliably regardless of the order which I pick up mines or grenades.
However the problem remains where for example if I bind mines to X, grenades to C and the rocket launcher to V. If I don't have mines and grenades, and I press X or C it will switch to the rocket launcher.
In other games, if a particular weapon is empty, pressing the button for it doesn't do anything, which is my preferred behavior.
I'm fairly happy with it at this point