High Imperial Roman army vs Late Roman army

[C Crastinus]

Auxilliaries didn't have a ton of missile weapons like the Late Romans did. Plumbatae and Lancaea/Veruta would have rendered a large portion of a principate shields useless.

In the situation of plumbatae impacting the rounded scuta vs. pila impacting flat shields, I think the pila would disable more shields, but there would have been at least twice as many plumbatae as pila thrown, so maybe it would have been a wash. I would still give the advantage to the Principate legionaries in the ensuing hand to hand combat, all other things being equal.

It's too bad we can't really put this to the test. I suppose we could have reenactment groups from each period duke it out. That wouldn't be a perfect test, but I'd still pay to watch such an event.