Those Varberger 757 actions were built by Sako. They should be plenty strong enough for modern, higher pressure loads.My varberger 6.5x55 is the most accurate rifle I own. CFE223 works well with Barnes 115,120 and 127 grain and it likes RL16 with 130 CX.
Most folks won't load their modern actions or even 98 type actions to their full potential, because they don't want to exceed loading manual specs or they rely on factory made commercial offerings, which are mostly loaded to specs appropriate for the 96 Swede actions.
I remember a fellow on this site, quite a while back, who mentioned it was possible in Norway/Sweden/Finland to purchase loads which were unsafe in the 96 actions and purpose built for stronger actions, such as the 98 Mauser and others.
That being said, I've seen "COMMERCIAL" 96 Swede actions chambered for cartridges generating much higher pressures straight out of the factory.
The fellow was going on about a 96 type action which was chambered for the 284 Winchester, which is no slouch.