Originally Posted by ODAVID
Please address the following questions I have:
3. Some say it does not make a difference but measure the inside volume. I am getting sick of hearing so many different thoughts with no meaningful evidence. What do you recommend?
Thank you I look forward to reading your thoughts
Measuring and sorting by the interior volume of the brass is certainly the best method of establishing resultant pressures and reducing ES/SD. But it's a tedious process. Whether it's worth it or not would depend on the the user's goals. If you're trying to set a new world record in benchrest competition - probably worth it.
I know for fact that widely varying interior case capacities will affect pressure, velocity, and consequently POI. I've experienced that and proven it to myself by switching brands of cases of widely differing weight and interior capacities. I've had POI shift 2" at 100 yds. This was before I started to get serious about hunting at long range.
How close is close enough when it comes to volumetric consistency of the interior of brass casings is a question that is really dependent on the level of accuracy you're striving for, the time you're willing to invest, and can probably only be answered by you.
But interior case volume it the physical property of importance. Weighing cases is a shortcut method in the effort to identify and obtain uniform interior casing volumes. Problem with weighing cases is the weights will change due to variable external case dimensions which has nothing to do with interior volumetric capacity. Therefore measuring interior case volumes is the only way to go if you're trying to leave no stone unturned in the quest for consistency, accuracy, and precision.