I did a ladder test with 123 Sierras and started at 45grains of H4350 and went up in 1/2 grain increments to 48grains.
47. 5 and 48 grains were too hot.
46 and 47 grains looked promising but i didn't get round to shooting them at 300 yards as I've decided to use 140 A max's and just about settled on a load for these.
Hope this helps.
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