Evidence for legionary vs auxiliary helmet patterns

[Tim Edwards]

I think we went a bit OT! (albeit an interesting diversion)

My question:

Why are we seeing iron imperial gallic helmets in Augustan Roman military graves, but seldom ever copper alloy ones?

I do not believe the answer is that the copper alloy ones were all recycled. Some of these graves with iron helmets also contain copper alloy paterae and situlae as part of the assemblage.

Specifically I am thinking of the grave panopolies at Idria, Verdun and Nijmegen. Does anyone know of any further graves with infantry helmets, of either copper alloy or iron?

My own contention is that the deceased 'iron helmet wearers' were in this instance buried according to their own native traditions.
So why the lack of copper alloy helmet wearers? - maybe different burial traditions...