Pyscodog,
Not knowing the specifics of your rifle, I am going draw on basics.
Do you know your COAL,cartridge overall length) when touching the lands? I use re-sized and unprimed brass with a slot cut in the neck shoulder. I then hand seat a bullet and the gently chamber the round. The touchy part is when you want to extract the built-up dummy round without moving the bullet. I keep my fingers on the brass to prevent the ejector from doing its job, namely flinging the brass out of the action. After having successfully removed the dummy round, I then measure the COAL. Remember, this is only good for this specific bullet. I then build up another dummy, without the cut slot, and try the round at the measured COAL for chambering and magazine feeding issues. After adapting the COAL to correct the issues, I then figure out a mid-range powder load. I then build up 5 rounds at COAL. I then build up 5 rounds at COAL -.003 in. Again at COAL -.006 in. The extent of this load exercise and reduction in length for me is realistically down to COAL as described in the reference books.
Shooting starts with a clean rifle and I shoot 5 fouling shots.
I dry-swab the bore after those shots. I shoot the first load,COAL), dry-swab, cool the rifle. Records of group size, case condition must be kept. You will notice that the group size will change as you shoot, some combinations will be good, some not. I have found that group size usually starts out average, will reduce in size, will again enlarge and the again reduce. I understand from this that barrel harmonics are the deciding factor. I have taken the load that shows the reduction in group size the second time to be the most promising. Once you have figured out which COAL your rifle likes best, then you can start playing with varying powder loads.
This may be long and dry but I've found out that this method, using the same powder load and differing bullet seating depths to figure out the best starting combination, actually saves time because you only change one parameter at a time.
Keep us informed of your progress,
Tazzman