Just a thought, don't know if anyone knows. At the time when J'OC was loading 62/H4831 did the 130 Nos. Ptns. have the relief groove in them? Those bullets would probably have decreased the bearing surface and reduced pressure a bit.
I have no idea during what time periods the bullets with the relief grooves were produced. Kind of curious since I happened on some of this style for my .338 WM.
