Re: mil-spec 168gr ammo
I prefer an alternative to MilSpec for the M14/M1A. 175gr SMK, Rem brass, 42.2gr IMR-4064, and a large rifle primer, 2.815" Max COAL. F/L resize every time, no shorter than is necessary to chamber the round.
For Match shooting, I used the Fed 210M. If (and only if) extraction becomes an issue, it could be worth considering a small base resizer die. Always load semi's so the bolt is required to strip every round out of the magazine.
The 168 should work fine as a substitute for the 175SMK; it was a practice with the arsenals to use the same charge for several different bullet weights. But the 175 is the preferred bullet over the 168 for distances exceeding 800yd.
Be aware, published charge weights for USGI arsenal loads were estimates; each lot was actually loaded to a spec based on test velocity, not charge weight, as is duly noted in the Barnes book. Blindly using them could result in pressure issues due to powder variations over the decades since they were published.
Greg