I'm hoping someone can help me out with this concentricity issue. I'm a fairly experienced reloader. I use the Redding competition dies to load my 300 RUM and concentricity as measured on my digital Sinclair gauge is great--1.5 thou or less, and often all zeros. So I recently started reloading for my 280 Ackley with Nosler Custom brass, as its the only commercially produced brass for that cartridge. It comes out of the full length RCBS resizing die perfect almost every time--the necks measure a thousandth or less on the concentricity gauge. The occasional brass over that is run through the resizer a second time and always fixed. Then I trim to length and put a square VLD chamfer in the throat. I lube with graphite and load with a Redding competition seater die. With both the standard accubonds and the new long range accubonds, I very seldom get less than 2 thou of concentricity, and most come in right at my self-imposed limit of 3 thou. About a third run 4.5 to 6.5 thou, and I don't know why. Never had that problem with my 300 RUM using the cheaper Remington brass. I do also have the Hornady "neck bender" gauge that straightens the rounds out to 3 thou or less fairly easily, but I would rather not do that. It seems to me that the vast majority should be coming off the press at well under 3 thou concentricity, as they do with my 300 RUM. The only process that I can think of that I do not perform is turning the inside of the case necks. I have never found that necessary with the Remington brass. Perhaps the Nosler custom brass requires it for some reason? Any ideas why I might be having this problem?