There are many errors on their drawing, such as the shoulder angle, which is supposed to 35 Deg, not the 17.5 Deg they are showing. I sent them a notice a long time ago, and they said they will correct it, but they never did.
To add to the confucsion, then;
They stipulate 56.50mm, but their English measurement translation does not fit this; 2.244" - is, in reality 57mm (56.50mm = 2.224"...)
Now since Norma is the only "Standard"....
if we go with CIP's standard for the 9X57 we get; Max ; 56.80mm (2.236") Min or "Trim-to" (- 0.20mm) = 56.60mm (2.228")
CIP's states 57mm (2.244") Max for the 8X57 and min or "Trim-to" would be 56.8 mm (2.236")...
Under CIP, the 7X57 is the same as the 8X57. Check Lapua's site for these.
SAAMI's "standard" says 2.240" Max / trim-to Min 2.220" for the 8X57 and 2.235" Max / Trim-to Min 2.215" for the 7X57...
My opinion; since this round is a low pressure one, it won't hurt much if you trim at 2.215", but I suspect Norma wanted to mean 57mm MAX and 56.5mm MIN / Trim-to, which would mean; 2.244 MAX / 2.224" MIN.
Anyhow, because of this weird situation, and lacking better infos, I personally trim the 9.3X57 cases just below 2.224".