found his old book in the online lib.
alone for the type Weisenau, H. Russell Robinson had different classes
Imp Gallic goes from A-K with subclass naming from locations
Imp Italian goes from A - H
at least 4 classes are considered derivates of this helmet, Auxiliar helmets A - D
but after 1975 a lot of work of adding classes, locations, variations proven from sometime only two or even one archaeological found are given, differently named in different countries
how fine this differences are, can be shown from the reenactment scene.
a simple start i.e.
for sideviews mainly
here you find also a clue, that the
Unit_ROM_Mid_Empire_Legion4 (and others)
is close to the Aquincum helmet
which however is not a that large jump in the timeline, that you could say it was used mid. imperial time
...not paid by AGEOD.
however, prone to throw them into disarray.
‘Everything is very simple in War, but the simplest thing is difficult. These difficulties accumulate and produce a friction which no man can imagine exactly who has not seen War . . . in War, through the influence of an infinity of petty circumstances, which cannot properly be described on paper, things disappoint us, and we fall short of the mark.‘