Here is a great example of a few folks not carefully reading what the OP posted and turning this thread into a circus. I'll reiterate, AbeS fires his loaded test rounds from lowest to highest, exactly as he should be doing. All he was basically asking is why the various reloading manuals exhibit such disparity in their "MAX" loads. Regardless of who the reloader is, they have to use
some method for determining how high to go with charge weight when setting up a powder test. AbeS's method is simply to use the MAX value from a reloading manual as his absolute highest charge weight in a test. He starts
shooting the test rounds with the lowest charge weights and works up, and there is absolutely nothing wrong with doing it this way. Nothing.
Abe - Reloading manuals have no way of knowing what brand of brass you're using (i.e. internal case volume), the burn rate of the specific Lot # of powder you're using, the brisance of the primer you're using, and maybe a few more variables that are not coming to me off the top of my head. It is also necessary to factor in the notion that some reloading manuals may just be generally more conservative with their published loads than others. Because of these factors, it is possible to find published loads in different manuals where both the starting and MAX charge weights are NOT the same, even if there is some overlap in the middle. As long as there are different charge weight values published in different reloading manuals, your approach of looking for a MAX load as your upper limit may cause you to encounter this issue.
My suggestion would be to use a slightly different approach; i.e. buy/obtain yourself some reloading software. I use QuickLoad (top link), but there is also GRTools that some members here at A.S. favor (2nd link).
A tool similar to Quickload but for free.
www.thereloadersnetwork.com
Regardless of which you use, what these programs offer are a very wide range of preset, selectable cartridge, bullet, and powder files. Some of the variables, such as powder burn rate, are user-adjustable, to allow the user account for Lot-to-Lot variation in powder, temperature, different primers, etc. Basically, to get started one needs to input a series of measurements from their actual loaded rounds (i.e. bullet length, barrel length, COAL, case length, case volume, etc.). Using a preset powder burn rate for the powder selected from the menu, the program will provide outputs for a given charge weight such as cartridge fill ratio, pressure, barrel time, and velocity. Because the programs contain a only single preset powder file for any given powder, the initial program output values may or may not be close to the real-world values. That is because of Lot-to-Lot powder variation, primer brisance, case volumes, etc. All one need do is to use a suitably reduced load (for safety reasons), then go out and determine actual velocity for a few loaded rounds. Once back home, the user can then adjust the program for actual temperature, then change the preset powder burn rate value until the
predicted velocity matches the
actual recorded average velocity. I refer to that process as "calibrating" the reloading program to a specific setup. Once the program has been calibrated to a given setup, the predicted responses (outputs) are usually quite good.
I mention this here not only to bring the innate value of these reloading programs to your attention, but also because you could actually do something similar without actually having one of the programs. For example, you pick a charge weight common to the various reloading manuals you have for your specific cartridge/bullet weight/powder combination, but making sure that the selected charge weight is at the
low end of the range. You load up a few rounds, then determine actual average velocity from those loaded rounds. Once back at home, it should be fairly easy to determine if your actual real-world velocity results line up with the values reported in one manual versus another. This is a "seat of the pants" kind of approach, but one that would very likely allow you to rule out using the load data published in some of the manuals that clearly did not match up well with your actual test loads and therefore might be reporting MAX loads that are too hot. The only real downside to this approach is that it does require loading few rounds and making one extra trip to the range before actually starting the load development. Because of the way you already do your testing, it may not offer any real advantage to you other than peace of mind if some of the MAX values reported in your manuals seem excessively high. With the reloading software, this calibration step is essential for good results. In any event, best of luck with the process and give those reloading programs a look. Most of the people that have them find them to be extremely useful.
