Question about ranged weapons and rate of fire:

In Runequest, which I am playing soon, ranged weapons such as bow, crossbow, and sling all have a "load" quality which tells you how many actions it takes to reload. This is designed to compensate for the fact that melee characters often have to spend actions actively defending themselves or maneuvering, while ranged attackers are more likely to be able to use all their actions on reloading and shooting as fast as they can.

* Bows have load time of 2 actions.
* Crossbows are 4 or 5 actions depending on size
* Slings are 3 actions.

Most characters get 2 to 4 actions per 5-second round, and remember, some of those actions will be spent parrying or dodging incoming attacks.

So, are those load times realistic? The bow and crossbow I'm okay with, but I'm not sure Slings should be slower than a bow. I mean, how long does it really take to grab the other end of the sling and drop a new rock/bullet in the pouch?