The following's good info on .308 Win. loads for 22 inch barrels at longer ranges. Note some of them are way over max safe SAAMI pressures, but they worked well in M14's
The Rifleman's Journal: Cartridges: 7.62 NATO Long Range Match Cartridges - Part 1
The Rifleman's Journal: Cartridges: 7.62 NATO Long Range Match Cartridges - Part 2
Over the years, one load's been popular and if it doesn't work in your barrel, you may need another barrel or your barreled action refit (bedded?) in the stock. And the shooter may well need to be replaced, too. 43 grains of IMR4064 under a 175 Sierra HPMK with the bullet seated to touch the lands when chambered. 42 grains if IMR4895's been a close second. Sierra's 168's and 180's in HPMK style are not too good for the longer ranges; they tend to go subsonic before 1000 yards when fired from .308 Win. cases. I doubt you can shoot 155's fast enough (3000 fps) out the muzzle of a .308's 22 inch barrel; they need to leave that fast to remain supersonic in most atmospheric conditions.
Wolff large rifle primers are among the best for accuracy. So are commercial cases. Full length size your fired cases correctly. Ensure your rifle's firing pin is up to factory specs; weak ones cause poor accuracy at the longer ranges as velocity spread will be too great.
Bullets need to be a few ten thousandths inch bigger than groove diameter for best accuracy. Slug your bore then compare the lead ball's diameter to what your bullets are. If the bullets are smaller than the barrel's groove diameter, don't expect great accuracy, but it might happen.