I'm back with notes from my reloading log.
Gun - Heym Mod 22S 7x57R/20 ga combo, 24,5" barrels, claw mounted 4X Zeiss scope. Purchased new by me in late 1983.
This gun was purchased for hunting and still gets used every year. It was never intended to be a range rifle for punching paper, but it is very accurate, producing many sub one inch three shot groups although larger groups will open up somewhat. Never required more than one or two shots on game so five shot groups were academic. Mountain hunting for sheep, goats and caribou were the main goal with moose, bear and birds next in importance.
My loads were developed for maximum effectiveness on game at ranges to 300 yards max, preferably under 200 yards. All loads were originally sourced from loading manuals current at the time and are safe in my gun, the empties fall out and case life is excellent. There was no attempt to develop and use maximum loads and I can not take any responsibility for the safety of these loads in your gun, that is solely your responsibility.
Although I did some initial testing with easily available cup and core bullets from Hornady, Nosler and Speer, because this was for hunting my focus was on premium hunting bullets and the only ones commonly available at this time were the Nosler Partition and the Speer Grand Slam. All brass was Norma once fired or new, all primers were Winchester LR. Powders tried were those regularly available in the early 1980's. Partitions were more accurate in this gun. Chronograph velocties were five shot averages over an Oehler 33. Bullets were seated out as far as possible without touching the rifling while maintaining at least one caliber width of seating depth. These loads evolved from starting loads of approximately 10% lower.
The loads.....
140 grain Nosler Partition
41/ IMR 4895.............2750 fps
42/ IMR 4064.............2670
48/ W 760................. 2660
48/ IMR 4350..............2678
50/ IMR 4832..............2677
52/ Norma MRP...........2691 - note - pressure signs were modest and I later boosted this to 53 gr but never crono'd it
53/ Norma MRP....................standard hunting load.
175 grain Nosler Partition
45/ IMR 4350...............2437 fps
47/ IMR 4832...............2508
50/ H4831....................2474 Standard hunting load
The listed hunting loads are well proven on many species, providing excellent accuracy in my rifle, break heavy bone with deep penetration. They do all that I require from this rifle and do it well, you can't get any deader than dead.
Norma MRP is hard to find, it sometimes shows up at gun shows. In several .338 Win Mags Reloder 22 was an exact replacement, load for load duplicating MRP for velocity, case expansion, case fill but I have never tried it in the 7x57R because I have adequate quantities of MRP.
This is an excellent hunting caliber, especially in light rifles, good luck.