Big Ed,
Yes, a number of bullet and loading companies use strain gauges, but they’re also members of SAAMI. This means they exchange information with other members of SAAMI, and if they run into oddities they can check with a couple of major companies that use piezo equipment, both of which account for that vast majority of powder distributed in the U.S. They do check pretty often, and in fact one of the bullet companies you list has had one of those piezo labs do their testing, rather than use a strain gauge. One of those piezo labs, in fact, is kept very busy testing loads for a variety of companies, not just the loads they publish for their own powders.
One of the heads of one of those major labs said “with strain gauges there are too many layers to result in anything more than general pressure comparisons.” And yes, he has more experience with strain gauges than any of the hobbyists who buy a Pressure Trace and suddenly think they have a ballistic laboratory to provide THE TRUTH, rather than the fiction the big companies show in their data.
In that guy’s opinion, strain gauges are reasonably useful for general pressure comparisons. He specifically mentioned comparing the pressure of handloads to factory ammo, giving the home handloader a reasonably useful indication of the pressure of their loads, certainly more accurate than guessing from traditional “pressure signs.” But the results aren’t accurate enough to work up factory ammo, or obtain very accurate standard deviation numbers for analysis.
The other problem with German’s results from his strain-gauge experiments is they often involve a very limited number of cartridges, and usually cartridges of a very limited type, usually relatively small in capacity. The indications he got from the primer test are NOT valid for all rounds, because some definitely benefit from much hotter primers, however you want to define “hotter.” This is even true of some pretty small rounds, with some powders.
The comment about primer flash photos was made by a guy with as much time (several decades) in professional pressure labs as the guy who provided the comments on strain gauges. He helped design AND improve a bunch of different primers over the years, for all sorts of cartridges, both civilian and military rounds, instead just taking their photos and running a very limited test with one type of round.
German is also the guy who came to the conclusion, through strain-gauge tests, that Reloder 17 was “a new paradigm in powder performance.” He tested it in one small cartridge, the 6xc, against a small number of other powders, and RL-17 did what he said. But a LOT of powders will also outperform others by a considerable margin in certain rounds, and that doesn’t mean they’re magic.
His “news” that Reloder 17 resulted in an extra 200 fps at the same pressures as other powders was instantly all over the Internet. And a lot of people believed it, because there wasn’t any professional pressure testing of Reloder 17 available at the time. Handloaders working up loads with traditional pressure signs often DID get lots more velocity, because traditional pressure sign usually don’t show up until around 70,000 PSI. (I know this from work done in a professional piezo lab.)
When professionally tested data for RL-17 finally appeared, it turned out it was a good powder, but certainly no new paradigm. In a few rounds it does gain as much as 100 fps over other powders, but even some other new Alliant powders, such as 4000 MR, get more velocity at the same pressure in other rounds. Even old powders like RL-19 and 22 will sometimes beat 17 in particular applications.
Don’t get the idea from all this that I don’t like German’s work. I have been reading it for years, and do find much of his information interesting and useful—as far as it goes. But like the primer test and his conclusions about RL-17, it’s often very limited in scope.
I was very glad when Denton posted the information about the minimal differences in pressures recorded with SAAMI and CIP systems, because I was thinking about posting the same information. I was actually in the Western Powders lab right after they’d just finished up their tests on all that, and the head ballistician found there was less than 1000 PSI difference in the two methods. But if I would have posted that, instead of Denton, you would have instantly gone ballistic, as they say.
The Internet is a great resource for information, but it is far from the only resource. I have spent days in various pressure labs around the country, and even worked briefly in a couple, both strain and piezo, to get a better grasp of what’s goes on. I’ve also spent hours and even days talking to the various techs in those labs, including the head guys, and learned things they’ll never post on the Internet, because they’re far too busy testing pressures day after day, year after year. They’re not running Pressure Trace tests with a few cartridges and powders and then posting the results.
