and as i've said this does not solve the problem at all as that apparently is not what the game reads for that button when there is an attachment on it.
i'm still waiting for someone to give me the proper word to go there.
+actionslot 3, or any other actionslot or +actionslot does not make anything playable. putting +attack there makes it fire regularly, and so on. leaving that particular button out completely returns unhandled and unbound script. so someone give me the +combination that makes the key grenade launcher...
question still not answered.