Almost unheard of in the shadow of the 9.3x62, and the cordite fuelled 375 H&H
I got to know the Sako employee who developed the .370 Sako some when touring the Sako factory and doing a little hunting in 2015. (Have his name in my notes somewhere, but can't think of it right now.) He said the cartridge wasn't really intended to be an improvement over the 9.3x62 or 9.3x64. Instead he just wanted to give hunters something else to talk about!
At the time he'd taken it on one safari, and hunted moose with it in Finland--and of course it worked fine.
“Montana seems to me to be what a small boy would think Texas is like from hearing Texans.” John Steinbeck
