Lol, if you think your gun is to explode at 1 or 2 or even 3 grains below a reloading manual’s published max charge weight for a given powder you should not be shooting it at all.
If the OP wants piece of mind and lacks sufficient confidence the rifle will function properly to the extent he wants to remotely fire it on a test stand, he should have the gun checked out by a gun smith. If something is going to go wrong, its going to go wrong regardless if you “light charge” your hand loads or not. And if it functions fine with “light loads” but fails catastrophically when normal full power loads are put through it, what has he gained?
And where are you getting the number “60” from? Typical PRC charges across popular powders like H1000 are in the high sixties to low-mid 70s for the PRC with 200-230g bullets, for example (i have no idea what bullets he’s planning on running, just picked that weight range randomly)