How to implement the "ranged kit" for rifles.
This is basically what I had come up with too. I think there should be a cast time that roots you in place though, and relatively long (5-10 seconds). The idea would be for it to more or less be a permanent choice, and not something you can hot-switch in combat. That would keep it more in line with the other weapon sets for engineers.
I seen some one suggest this a while back. And I liked it. Only to be fair the pistol(s), shield, and harpoon would also need a second weapon skill set.
It could be incorporated as part of the class function. seeing as our current tool belt tends to be packed full of under performing skills with longer than necessary cooldowns with only a few exceptions.