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As I understand, you were previously setting up to full length size, as recommended by manufacturers, by turning the die in to touch the shell holder plus about 1/4 turn. Now you intend to "bump" the shoulder some amount compared to a fired case.I have been full length sizing my brass and have a good load worked up but I'd like to start just bumping the should back. Should I expect the same, worse, or better groups with the same load?
Yes, this exactly. Thank you.As I understand, you were previously setting up to full length size, as recommended by manufacturers, by turning the die in to touch the shell holder plus about 1/4 turn. Now you intend to "bump" the shoulder some amount compared to a fired case.
In the interest of reliable chambering in the field, I suggest bumping the shoulder about 0.003" compared to a fully fire formed case. Keep in mind that it may take 3 firings to fully fire form a case to the chamber.
In any case, I expect your groups will be the same.
My needs are pretty basic in terms of precision - just looking for minute of animal. I shoulder bump my bottlenecks (and anneal) to help preserve the brass, especially my .338 WM.I have been full length sizing my brass and have a good load worked up but I'd like to start just bumping the should back. Should I expect the same, worse, or better groups with the same load?
Sometimes the press wins, and sometimes the case wins. If the sizing die is setup without firm contact between the shell holder and the die (cam over), variations in the slop in the press, brass hardness, case lube, etc. can cause the cartridge case to datum (bump) to vary considerably.......
One of the things to keep in mind is that you can have some slop in your reloading press, die threads, and the biggest factor is the brass springback. You really have to be on your game to be bumping shoulders .001". I don't own high dollar reloading dies, so maybe that's a factor, but I was never able to keep consistent headspace on a non-annealed case under .004". Less than that and springback became such an issue that headspace could vary plus or minus .002" case to case. Once you get to that .004 or .005" you are working the brass enough it takes a good set. With annealed brass I am able to get that down to the .002" to .003" range.
I bring up annealing not because it is for headspace, but because it can have an effect on accuracy. Consistent neck tension, the actual resistance to bullet pull, not the diameter measurement, is a very critical component to getting great accuracy. I've even gone so far as to have tried neck sizing only. Accuracy was unaffected. The only thing that changed is that chambering got really hard quickly. I'm sizing my brass with less shoulder bump, not because it is more accurate, but because it maximizes case life. Bumping a shoulder back .006", not annealing, and that case might be done in 5 shots. If you only bump .0025" and anneal every loading (some do every 2-3), then case life can skyrocket. I mean really go forever. If you shoot really hot loads your primer pockets may loosen over time. I've gotten 30 loadings on some 308 brass before. At a certain point you loose them, or they get dinged or something, but they don't develop neck cracks or case head separations if you do this.
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Amen brother.I neck size only using a Lee collet neck sizing die. Brass goes with each specific rifle in cases of multiple rifles in the same chambering.
FL resize only when the bolt is stiff to close.
P