[Lynn Eades]

The Australian pattern track has a lead plug that holds a shorter straight pin in situ. There is a smaller hole on the opposite side to allow for the use of a track pin punch. The Vickers light tank MkVIB also used the wide horn track (with a headed pin)and would have been the origin. In practice the both were mixed and out here at least both kinds of track are found. (I have some of both)
The point here is that the Swiss may have gone with the lead plug and hence the shorter pin (without the track being narrower?)

Edit: To be clear, both types were made for the Aust. pattern carriers.