Not sure why HVA went with 1/12 on the 7x57, certainly not the norm for the time period. Even the 7mm mags were 1/9 in the same time zone they produced.
They made very few 7x64 but I'm not sure the twist rate in those, but should be faster then 1/9.
I only have 3 1600 series, early 30/06 with steel trigger guard, later 30-06 with alloy guard, and my favorite a late model (skogis) Dahlberg in 6.5x55 with 21" barrel. It's not blingy like the majority of the Dahlberg styles, pure hunting style with a flat recessed cheek piece, short LOP, and light weight. When you think about it, a Monte Carlo cheek piece pushes your face away from scope alignment, Dahlberg as strange as he was had the idea to slope the cheek piece the other way for better scope alignment. It works well, and I'm surprised nobody else has ever picked this up.
Few pics here, I like it more for function then uniqueness. And I don't find the triggers bad at all for hunting, bit heavy, but nothing intolerable.
https://www.canadiangunnutz.com/for...-####-ALL-MODELS!!!/page33?highlight=Dahlberg