This thread was fun to read through. I feel like I'm hanging out with some potential benchrest candidates, most of which aren't going to be able to reach the minimum OCD level required for a full-on benchrest infection.
WRT scientific method, the diagram you gave is part of the process. The history of scientific method (SM) is fascinating to a nerd like me. Many people credit Francis Bacon as the key developer of SM and you can find all kinds of support for that point of view:
Baconian method | Inductive reasoning, Scientific method, Empiricism | Britannica
Baconian method, methodical observation of facts as a means of studying and interpreting natural phenomena. This essentially empirical method was formulated early in the 17th century by Francis Bacon, an English philosopher, as a scientific substitute for the prevailing systems of thought, which,www.britannica.com
In fact, the foundations of SM (not S&M, you pervert) date back at least as far as the life of Ibn Al Hytham (965-1040AD). Some people consider him to be the first scientist:
A dude named Jim Al-Khalili wrote a book titled "The House of Wisdom" that is an excellent read on the history of Arabic science. Chapter 11 is titled "The Physicist" and it centers on the work of Al Hytham. The chapter opens with a quote written by Al Hytham about peer review in science that, way the fuck back there around 1000 AD, reveals the fundamental, philosophical core of the scientific method, which is to find ways to keep preconceived notions and biases from resulting in acceptance of the wrong hypothesis:
"The seeker after truth is not one who studies the writings of the ancients and, following his natural disposition, puts his trust in them, but rather the one that suspects his faith in them, and questions what he gathers from them, the one who submits to argument and demonstration and not the sayings of human beings whose nature is fraught with all kinds of imperfection and deficiency. Thus, the duty of the man who investigates the writings of scientists, if learning the truth is the goal, is to make himself an enemy of all that he reads, and, applying his mind to the core and margins of its content, attack it from every side. He should also suspect himself as he performs his critical examination of it, so that he may avoid falling into either prejudice or leniency."
Bold added by me - I'm not sure they even had bold font back in AD1000 and the above demonstrates that those pontificating motherfuckers didn't teach how to avoid run-on sentences and if I work at it hard enough, can show that some of us don't avoid them very well either, while preaching from a creaky crate in the middle of the Hide town square reloading forum. The point I'm making is that, if one wants the scientific method to work , first we must doubt what we believe to be true. We have to be our own harshest critic, so our peer reviewers can dig deeper after we already dug a pretty deep hole of self-doubt.
Thanks for the comments, i found them interesting. I am familiar with the scientific method from a prior life as a research engineer.
Started the thread because it became clear that the dimensionally consistent but soft Norma brass will not survive long enough if loaded to 0.5 grains below max (usually a decent safety margin for a temp stable powder), which would have forced me to run at about 2780 fps, and maybe get 5-7 reloads. Or run at 2600 and maybe 12-15 reloads.
I was trying to figure out a “predicted case life equation”: How far to back off from max powder charge to get a desired case life nr like 10, if you are forced to use less than premium brass. The arbitrary target of 10 was chosen based on lowering cost per reload sufficiently.
Also wanted to ask more experienced folks about best experimental design: What to measure, how and where, what instruments to use. Is the growth in the primer pocket diameter a linear effect - or is it significantly non-linear? [As it turns out, there is a lot of initial expansion and then it gradually slows down.] And general methodology, how best to fire form, etc. Several people provided helpful advice.
Once the ADG brass arrived, i found that the case head is much harder, and it is now clear that you would need to run at unacceptable pressure if you insist on exactly 10 reloads and no more. Clearly that would not be wise (or safe).
Eventually, i found a good wide flat node a safe distance away from max, and case life ended up better than required. Happy outcome - and no need to “science” the problem into submission anymore. Proved to me why you should stay away from any caliber where top quality brass is not available yet.
Based on the speed difference between my 28” and my 30” barrel (both cut with the same reamer, and fired brass is interchangable), every additional inch of barrel length buys me 39 fps with slower burn rate powders like 4000MR or H4831. The choice of a 30” barrel added over 200 fps in speed compared to a 24” hunting barrel (what Hornady’s load manual is based on). Hornady’s 11’th addition load manual lists 2650 fps as the max attainable speed for a 220 gn projectile, using Winchester brass. So 2850 fps is not really surprising.
Charles Greer broke the NBRSA 1000 yard heavy gun world record with a 300 WSM rifle with a 30” barrel shooting 220 gn Berger bullets into a 2.8” ten shot group (100-10X score), running at 2800 fps, without HBN. The Australian pair Mark and Sam, famous for their Youtube ELR videos, managed to run a 220 Berger bullet at 2900 fps from a 27” barrel using Retumbo. The Lee manual list H4831 as achieving 2645 fps from a 24” barrel for 220 class bullets, add 200 fps to that to account for the extra 6” of barrel length, and you are at 2850, even without HBN. With a slow enough powder, long barrel length can add a lot of speed, while faster powders will give a more modest speed increase.
Yes you get only slightly better wind drift at 2850 than you would get at say 2600 (about 1.5”, so 10% less), but supersonic range improves by 250 yards, and the load is not unsafe in this particular setup. I don’t think you would get 15 reloads with an unsafe powder charge.
HBN can be used either to gain speed or to lower pressure at the same speed, and gain extended case life. Not recommending HBN for any and all applications, but if you want to reach the next higher node, and do it in a safe way, and if you have enough spare case capacity, then yes it is an option. Or if your case life is problematic, then perhaps try HBN and keep speed the same to preserve the primer pockets.
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