different guns like different stuff
Wheeler, not trying to be evasive but my son's 24 inch barrel gun is probably going to like something very different than your 19 incher.
Oh..to make a long story here is how I determine what load a gun shoots. I picked this up from a co-worker who use to shoot long range competition and holds a high master rifle card, this is just what more experience and better shooters than me recommended and I like it and use this system. It takes a long time to really do this, normally at least a full day on the range, now and then two plus lots of cleaning gear.
Primer..I happen to like Federal, must my preference they always seem to go boom in hot or cold weather with all of my guns. Other primers work for many people I am not here to bash any brand.
1-Load a dozen or more loads at the low end of your range, this is your base to compare everything else from.
2-Load shells increasing in one tenth of a grain..toward the upper end load you are considering. Yes..this is a bunch of shells you need to have them labeled or some way to keep track of each one and which load is in it.
3-At the range, you need 200 yards, from the bench ya start shooting with a basic three shoot group from your gun with the low velocity ammo. I keep a target on hand and record each shot on my "bench target" with my spotting scope. When I say record I have a good pen, put a X on the postion of the shoot, record the load in grains and number shot, so it may look like a 23 with the load of 48.9 grains. I label grains to make sure there is no confusion between shot number and weight of powder. Why 200 yards, gives the bullets a chance to settle down and do there magic, you do not see the variation as much at 100. If you are cleaning between shots, three shots works, if you are going to shoot a dirty barrel you will need to shoot 4 times to see where your three go after you foul the barrel.
Oh...forgot, you need to figure out if you are going to clean between shots or how many shots between cleaning. The advantage of cleaning between each shot is it gives you gun a chance to cool and you always know the basic barrel condition. It is up to you but be constant in what ever you choose. Please note if you are going to shoot with a dirty barrel you need to foul your barrel after a good cleaning which is what I use extra low velocity loads (your minimal load) Oh, why clean ( I have been ask this) if you are going to shoot from a fouled barrel, cause over time you will get too much copper build up and that will effect your grouping. This is an attempt to control some variables. I an not even going to get into sun location and all of the other stuff the long range guys talk about. Hopefully your wind conditions will not change to much but the less wind the better.
Ok..once your basic pattern is set, start shooting each round increasing in one tenth of a grain increments and record every bullet with every shoot. You also have to let your barrel cool between shots. (hey this takes time)
As you shoot each round you will see shifts where each bullet flies. Some will be close, sometimes you will see a huge change where the bullet flies. BUT...what you are looking for is where three or more bullets impact the same place very close to each other and are consecutive loads. Say you are shooting away and suddenly you see 55.1, 55.2 and 55.3 grain loads shoot a inch or inch and half apart..THIS is what you are looking for..a node in the Harmonics (this is what I was told guys, feel free to correct me) Anyways...if you set your reloader up to load the 55.2 grains and if your powder varys plus or minus a tenth you will still be in your inch range. I have seen a tenth of a grain make a 8 inch movement for a bullet so it can make a difference. You may find one node, in my son's gun we found two, one at 55 grains and one at 60 grains. Needless to say he practices with the 55 grain load and hunts with the 60. My 30-06 has one major node and for a production gun shoot delightful groups till it heats up.
Anytime you change bullet weights you get to explore what that new bullet likes to do out of your gun but the results are very accurate loads that work for your gun.
I have done this probably ten times between my guns and friends, so far the results have always been excellent but again, it takes time and lots of loads. Bring a sandwich to the range.
Hope this helps.