Originally Posted By: RiverRiderI wonder if there's a difference in the powder databases. My version of QL is 3.6.
Interestingly enough, my old Lyman 46th shows H335 with a 50-grain Sierra Blitz up to 30.0 grains of W748, with 3272 fps @37,100 CUP (this might have been enough to cause my little M70 to take its leave!). An old Winchester data pamphlet suggests 26.0 grains of W748 yielding 3160 fps @38,000 CUP.
There seems to be disparity everywhere.
I think part of it is that it is really difficult to measure pressure accurately.
I have worked in the ammunition business for longer than I will admit (though my 20yo Rug Rat says I'm 917 years old
)
I have a pressure gun boxed up in the basement, and some years ago, I ran tests on a bunch of ammo and none of it was "on the mark".
Which did not surprise me, cuz SAAMI took some calibrated pressure cartridges and sent a bunch to every outfit in the country that had a certified pressure gun, and asked them to report back what the pressures were - and the answers they got were all over the place.
And there is a reason for that - the people in the industry use pressure guns to meet "Their" standards - it doesn't make much difference what the actual "true" pressure is, because it varies from test barrel to test barrel, and also varies with the hysteresis of the plug or strain gauge - as long as "they" can repeat it from batch to batch (lot to lot), that's all that matters.
To the amateur/hobby loader, when they read that such an such a load develops 56,700psia, they actually believe that figure - in the industry, it is just a reference figure... as long as each batch says 56,700, then there is uniformity, so "... keep on keeping on" - that ammo measured by the company down the road might measure 51,500, or 59,500 - Quen Sabe - who cares??
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And that same load in "their rifle" will be no where close to 56.7Kpsia
Pressures have been climbing over the years - the original pressure standards for the 222 family of cartridges was ~45Kpsia - now, you can't find a factory 222 family cartridge that runs in the mid 40k's... they are all running 10 to 15 Kpsia higher.
It is a fascinating field, if you can be loose and understand the bigger picture.
My friends say I love making ammo more than shooting it
That's almost, but not quite - true.
Meow