Following AussieGunWriter's suggestion of up to 52 grains of H414 in a long throated 7X57 I loaded a single round at 50.5, 51, 51.5 and 52 grains of H414, WW brass, WLRM primers with 140 g. PRVI bullets. Then shot them through my ProChrono chronograph.
Results were: 50.5g. = 2830 fps, 51 g. = 2849 fps, 51.5g. = 2879 fps, and 52g. = 2898 fps. No signs of pressure at all with these loads.
The Hornady Manual Fourth Edition gives a maximum load of 52.4 grains of Winchester 760. So his advice agrees with this 1991 manual and appears safe in my rifle.
Now to test for accuracy because the load seems safe and is approaching the velocity of my old load using H205.
"It is wise, though, to remember above all else: rifle, caliber, scope, and even bullets notwithstanding, the most important feature of successful big game hunting is to put that bullet in the correct place, the first time!" John Jobson
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