Thanks, that's good detail.
I would assume the Garand sights were calibrated for the M2 load. But the 1903A3, maybe the M2, maybe the M1 load?
That's a good question because the Springfield rifle was used by many competitors at the National Matches between WW1 and WW2.
I'd think that the 172-grain load would be better at long range due to the better ballistic coefficient.
I agree.
I believe the M1 172gr had a BC of about .490. The M2 150gr was about .400 BC.
Also, I think it was O'Connor that wrote that the 172-grain load had to use a slower-burning powder which caused high port pressures and bent M-1 operating rods. So, the solution was to develop the M-2 load with DuPont 4895 powder, using about 49 to 51 grains, depending on lot number.
Another theory was that the 172-grain load had a maximum range of 5,500 yards which exceeded the safety zone of many target ranges. I think the 150-grain M2 load had a maximum range of 3,500 so was more easily contained within the safety zone.
Again, I'm posting from memory of what JOC wrote many decades ago.
