While I am new to this board, I certainly am not new to reloading nor to shooting and competing at long range, so I have about two cents worth of comments and observations. Take them for what they cost you and "your milage may vary" and no insects or other crawkling things were injured or kilt in the making of this post.
My first civilian experiance with long range shooting and reloading started with BPCR Silhouette in 1998. BPCR stands for "Black Powder Cartridge Rifle" these are the old buffalo guns of the period of 1870 to around 1915 or so. In reloading these old rifles there are many problems needing to be dealt with that smokeless powder shooters never deal with.
Case preperation can be just as big of a problem as any form of shooting, maybe worse. there is always after all that terrible fouling that must be dealt with. When I first started shooting BPCR I didn't really have a clue, but man did I learn quick. Building a load for a rifle that will be shot at typical Silhouette ranges of 200 meters --- 300 meters --- 385 meters-- and 500 meters and has a trajectory of a rainbow can try your patience. My come ups from the Chickens the 200 meter target to the Rams the 500 meter target is 67 Points or MOA.
In the begining I tried just about every reloading technique and trick I could come up with. I weighed and sorted brass till I was blue in the face, I sorted and sifted powder to remove the fines. Only shot bullets that weighed within + or - .2 tenths of a grain. I tested every primer known to man and even for a small amount of time weighed them as well. My scores did reflect improvement but still not what I was looking for.
What I found after doing the "PERFECTION RELOADING" thing for awhile that what really worked and I mean really worked was shooting and I mean a lot of shooting. When I finally got serious I was shooting 3 times a week and a match every weekend. All I did for a period of a year was cast bullets, load, drive and shoot. Some of those weekend matches were a 1,000 mile drive one way. I was shooting a Custom Built Meacham 1885 Highwall in 45-90 caliber with the best MVA Vernier Tang Mounted Soule sight I could afford. This site had a total of 44 MOA windage, and on the Rams one year at Raton in the National shoot I used almost every bit of that. In my first 32 matches that year my Ram count ( the 500 meter target) with Iron sights was 319 out of a possible 320. I am not a gifted or talented shooter, for me it has always been work and hard work. Trigger time, Trigger Time and then some more Trigger Time is just maybe the very best thing in the world for a shooter.
P.S. And I guess to stay on the subject of this post. I only shot Winchester Brass I always found it to be without a doubt the most consistant. And the case capacity of Winchester brass is at least in the 45-90, two grains more than any other Brass.
I shot this target on the 1,000 yd range at the Whitting Center. Rifle was a
Cody Ballard in 45-100 Caliber with Iron sights, and there are 15 shots in this group