Recoil results are not converted into kills any more - so you can forget that one! 
Recoils are coverted to kills in 2 cases ( there maybe more ), unable to complete a recoil ( I have been taking this as a full recoil move ) for a flee result and being unable to recoil when defending fortifications.
I think my ideas on the first case is up for consideration as it says under fleeing elements on page 41, '
It is destroyed if if it cannot complete the initial recoil. but as whether this means a full recoil or not is not clear to some ( I think the confusion comes from complete rather than start the initial recoil ).
When defending fortifications it gets more complicated ( if possible ), for example an expendale assaults a spear defending a fortification the factors ( ignoring any overlaps ) are 4 for the mounted 7 for the spear, if the spear is beaten and recieves a recoil result, it then recoils it's base depth, the recoil depth is not enough space for either the expendable to enter does this mean the expendable stradles the TF ( which is now difficult going therefore the expendable is killed ( another zone of death behind form combat? ) ) or does the spear move further back to allow the expendable to enter, if it is unable to make space ( due to being able to move back any further) is it destroyed ?
I have dreams about assaulting Roman field fortifications with Hannibal's expendable untrained elephants ( I see them crossing the TF's on rope brigdes or tunnelling underneath making them well trained indeed ).

William