AGM mod weapon selection function (pressing 1,2,3,4,5,etc) works. So it is literally a bug with the vanilla game config only.

Just a quick to bump to let you know this has not been fixed as of 6/25/15. I am still unable to bind any keys to "change gunner weapon." After changing my joystick binds I also lost the bind there as well. I am currently using only the "next weapon" to change weapons. I have read three posts in the BIS forums regarding this issue. So I know it's not just me.

dxdiag https://www.dropbox.com/s/jfi6m2auui5y9fq/DxDiag.txt?dl=0

Not sure what else to add. Vanilla load, gunner weapon switch function is broken. Tried two different keyboards now. Bound almost all the keys. Post 1.42 it no longer works. Did a clean reinstall, verified my game cache.

Firing near vehicles seems to induce the sinking. Definitely PhysX related.
Also experiencing loss of sound on left channel.