Pila range and how?

[Robert Vermaat]

Not having any source, just thinking practically...
Before receiving an attack... Could not rearward soldiers pass forward pila to the "throwers" closer up? Or even the "shields" up front could plant their pila for the "throwers" a few rows back?

No problem. Same with plumbatae - IF the front rank has enoug space/time to throw these at the enemy, it would be silly for the rear ranks to throw them (as long as you don't want the entire formation for a single 'mass throw'). So I think they were handed forward. Of course missiles can be throw after the formations make contact, and it was part of Roman army doctrine to do so throughout the battle. But for pila that seems wasteful, as these are charge breakers without a very good range.