I don't know about the 62 grain being the most accurate, as a Bushmaster and DPMS AR with 1:9 twist like 68 grain Hornady's and 69 grain Sierra's best. Best I could do was 5-shot groups measuring 0.25" to 0.50" with the 69 grain in the Bushmaster and 0.75" with the 68 grain in the DPMS. The 55 grain Hornady SP would only do around an inch or a tad more in those two rifles while a 55 grain FMJ held closer to 2.5" groups with the best handloads loads.
With my AR's the Winchester factory 55 grain FMJ shot the worse of any ammo tried and that's saying a lot.
In case anyone is interested in those loads:
Bushmaster:
Berger 65 grain with 25.8 grains of Varget produced 0.25" fairly consistently as did 69 grain Sierra with 24.5 grains of H4895.
DPMS:
Hornady 68 grain match with 25.0 grains of H335 and 22.5 grains of H322 did right at 0.75"
When firing 10-shot groups the best I did was with the Sierra's and that was 0.6" with the norm being an inch, more or less, and this was shot prior to 7AM with no wind conditions. With wind conditions, seems like good 5-shot groups are around 1 to 1.5 inches - I suppose wind flags might cut those down some, as going by "feel" sometimes results in one or two really opening up a nice 3-shot group
.