Dunno either, and can only guess at what Steve's point is about Homer Powley and the 4-to-1 Rule.
For those who aren't familiar with it, the 4-to-1 Rule is that any increase or decrease in the powder capacity of rifle cartridges of the same caliber results in about 1/4 that amount of potential velocity, with the same bullet at the same basic pressure. One example I've used frequently is the .300 RUM and .308 Winchester: The .300 RUM has just about twice the powder capacity as the .308, but does NOT produce twice as much velocity--a 100% increase. Instead the velocity increase, with the same bullet at the same pressure, is about about 25%, which is 1/4 of 100%. This rule does not apply to the SAME powder, but the powders producing the highest velocities in each cartridge.
I am quite familiar with Homer Powley's slide-rule calculator, having purchased one around 40 years ago--and still have it in my bookshelves, packaged in a manila envelope with all the accompanying literature. Can't figure out what the 4-to-1 Rule has to do with any of Powley's basic rules, except that it's another phenomenon derived by crunching the numbers from LOTS of pressure-tested data.
The only similar rule I can remember from Powley is that pressure with single-based powders increases at twice the rate of velocity--which might be called the 2-to-1 Rule. But that was derived from copper-crusher pressure data, not the piezo-electronic data used by the best pressure-labs today, which shows the velocity-pressure relationship isn't quite that simple, even with single-based powders. It varies even more with double-based powders.
Steve also seems to be arguing that pressure-judging by primer appearance works very well. Would love to hear if he can supply some data. I seem to remember Denton mentioning that he'd tried it, and found no correlation.
Apparently, the Steve to which you are referring is not me.
Still, I am sorry that i did not preface my post with a brief explanation. I was attempting to point out that it was hard at that time to keep up with the science. It was evolving quite quickly. Much like electronics and computers are changing now.
For example, I was thinking that Hatcher's work (and the work of others) was done before test equipment or methods had been devised or refined that could accurately determine over pressures within a case. Some things that people of the time believed have since been disproven. Using primer flattening or expanded bases might have seemed like a logical conclusion then, and few would have questioned it. Hatcher worked for the Ordnance Corp and his opinions were respected, and deservedly so. But science is always advancing, both the methodology and a better understanding of the chemistry.
Explosives and the science that explained it were advancing almost daily at the beginning of the 20th century. I have said this before, but in a very short time, we went from primitive single shot mechanisms using BP and firing lead balls, to smokeless, repeating firearms firing jacketed bullets, tracers, etc. It would have been an interesting time in which to live. What you learned in university was quickly eclipsed by new science.
Men like Hatcher worked for the Ordnance Dept for over 40 years and they saw a lot of changes. I think Hatcher and others can be forgiven if they didn't get everything right. Their work advanced our understanding of ballistics.
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