George

I'd have to say a Brno ZKK 600 would be a contender for a lightweight Mauser action in the calibres you mention.

Essentially a small ring size receiver with additional lightening cuts on the LHS and a counter drilled bolt handle.

My Brno ZG47 (a true large ring sized receiver) in .270 is significantly heavier than my Brno ZKK 600 in the same calibre for example.

Cheers

TM