There are some cartridges that you can't get the required data for online when it pertains to MODERN firearms that are much stronger than the original firearms the original cartridges were intended for.
Two of those cartridges are the 7x57 Mauser and the 6.5x55 Swede.
Both of these cartridges can be loaded to give some very substantial velocity increases with modern powders and modern rifles.
I was reading an old article written by Finn Agaard just after he left Africa to take up residence in the US. The 7x57 Mauser was one of his favorites.
As you most certainly know, this discussion has been going on longer than most of the people here have been alive. Finn went on in his article to mention that ALL FACTORY LOADED 7x57 Mauser ammunition was loaded for the safety limits of the M93 Mauser rifles. There were others in that era of course but it was considered to be a HOT cartridge when compared to the others available back in the day.
Finn went on to say that he was hand loading his 1898 model rifles, chambered in 7x57 Mauser, with 22 inch barrels, to verified 2800 fps without pressure signs. He mentions powders but not loads used. White Labs did the pressure tests on his loads at the time.
I can tell you from personal experience with my 7x57 Mauser built on a 1935 Brazilian Mauser action that I am getting slightly faster 2875 fps out of its 25 inch barrel. I use the same powder mentioned in his article and I worked up the load until I got to my personal satisfaction point. I've put close to 400 rounds through that bore with 50 cases. The cases were reannealed a couple of times but they still look good, without any incipient case separation signs.
I applaud your restraint but there has to be considerations made for modern technology. I fully understand WHY ammo manufacturers give their load data for the weaker actions and don't publish higher pressure loads, nor to my knowledge even suggest loading any hotter. The 7-08 would be a great alternative for someone that only uses factory ammo to get the most out of an intermediate case in 7mm.