For Match Grade ammo you can use Hornady 30-06 Springfield 168 gr A-MAX.
I believe other makers also make ammo for the Garand.
You could also install an adjusable gas plug and shoot commercial ammo. Just stay away from the heavier bullets.
My concern about the less than military or match grade is the primer on the cartridge. The bolt will dimple the primer on return and softer primers could be a safety problem. I found a store that sells Hornaday match grade for the M1, but it is pricey.