When you pick up an empty rocket launcher like NLAW and then pick up a rocket it automaticly reloads. The character then puts his weapon on his back, switches to the rocket launcher, put it in ready position (dont know the english word), reloads it, put it in ready position, put the rocket launcher on the back and finaly take the wepon from his back. Under this process you can't do anything else and this takes about 8 seconds. That is deadly in a fire fight.
I suggest take away the autoreload process atleast so you can reload when you feel its safe.

With a pistol in hand when you do this it's faster but still, the auto reload can be enoying in the wrong circumstances.
And also, if you just want to reload the launcher you wouldnt want to waste time putting your weapon on the back, just let it hang in the sling.