If you have good brass even thickness all around throughout the case, and the loaded ammo is very straight, has uniform neck tension, fits the chamber well (considering that semiauto ammo has to have a looser fit than that loaded for a bolt gun), it all comes down to other factors, that I see screwed up pretty uniformly by black rifle shooters. They are trying to evaluate loads without a set of flags, and have made poor to no provision for how the rifle is supported during testing. I take it that you want to produce the very best ammo that you can, for one or more of your ARs. In order to do that, you need to become familiar with how to detect small differences in accuracy, consistently. With a bolt rifle, this can be done much more easily, just from the ease of shooting. I take it that you do not currently have a way to look at brass thickness around the case, below the shoulder. Getting that capability would enhance your sorting ability, as would having some way to detect differences in bullet seating force. Beyond that, you need to be able to see differences in the bump produced at a given die setting, as well as neck diameter. Just because brass is the best obtainable, does not mean that it can be used as if each piece was identical to the other. Sorting is called for, and there are a lot more things that you can look at besides weight and volume. If you want to go the real rich boy route, and I have a friend who has, you have a state of the art, underground shooting tunnel built, and pick up the necessary equipment to test ammo, which would include a rail gun, with action bolts suitable to the various calibers that you will be testing, and barrels to match. That should keep you busy for a while. ;-) Good luck with your project. Let us know how it goes.
