Pretty much already covered here, but 46-47 grains of 4895 and a 168 was simply THE National Match load for decades. It's already been touched upon here, but always bears repeating, perfectly safe loads of well under maximum pressure, can and will damage the Garand's op rod if the burn rate is too slow. Go to 4895 or 4064, or something no slower on the burn rate charts, and no slower. Dittos on the comments about bullet weight. I'd recommend 175s as being best suited, but certainly nothing heavier than the 180s.. The old style Sierra 180s (longer boat tail, like the 190s) were really great, but then they changed the bullet and put the standard 168 BT on it to economize on tooling. Stick with the 175 today, as it's a far better option for this rifle.
Truly great rifles, and a fine history behind them, but they do have special care and feeding requirements!