SnowTrekker, 42 gr. of 4064 in light weight cases (41 in heavy ones) under a Sierra 190 has probably won more 600 yard and further matches and set more records in the .308's heyday as a match cartridge than all the others combined. You'll have to seat the bullet out to touch the lands, but not an issue when you're single round loading. There may be better powders these days, but unless they're producing no worse than sub 3/4 MOA at 1000 for 20-shot test groups, forget 'em.
Depending on whose data you look at, any bullet-cartridge combination will have a few grains spread in the max load listed. Such is life when all sorts of barrels and component lots and assembly plus testing procedures are used.
Ladder testing's popular but I think it's a waste of time unless you shoot at least 15 shots per load and with good stuff can shoot no worse than 1/4 MOA at 100 yards. 2 or 3 shots only gives a 10% to 15% probability of representing what a hundred shots will show. And the theory behind Optimal Charge Weight used in most ladder tests is severly flawed in reality. Besides, the accuracy level of the hardware (rifle and ammo) and shooting abilities of the software (human) greatly effect the results. Better stuff shoots more accurate than lesser stuff.
4runnerman, there are no fliers unless you call one. Every bullet fired goes to its intended impact point. Count all of 'em when measuring accuracy
US Navy Distinguished Marksman Badge 153
Former USA Palma Team Member
NRA High Power Long Range High Master
NRA Smallbore Prone Master