Go with manufacturers listed COAL to .050" under max mag length. Don't get all wound up in it, it doesn't make that much difference starting out. Pick a length. Make a dummy round or two setting your seating die up. Use them to check firearm function. Everything good, pull the bullets with a kinetic puller if you need those for load development.

Start at the listed starting load and work up in 1% increments. 3 rounds each is fine, you are working up to max listed or what your rifle will take. People like to stop well short of this point but its safe and pointless to stop without knowing the limits.

You should see good accuracy as you approach/reach max loads. Once you know what the rifle limits are and where you are seeing acceptable accuracy, go back and load best accuracy +/- .5%, 5 rounds each.

After that, you can play with seating depth in .020" increments to see if it helps accuracy but don't get too deep into "jump to the lands", it's a very touchy tuning knob with some bullets but with most tangent ogive bullets, it honestly doesn't affect hunting accuracy enough to be expending another box of bullets over.

HTH.