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Old February 12, 2013, 07:11 PM   #22
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Join Date: November 8, 2007
Posts: 2,001

The Speer GDHP is much shorter than the Hornady XTP-HP, which is the bullet used in the 13.0 grain max charge for AA #9 found in the AA data manual and the Hornady manual.

So, even with the COL set 0.005" shorter for the Speer bullet than for the Hornady bullet, QuickLOAD thinks there is 19% more powder space (for the basic case capacity set to 20.8 grains of H2O). So, an equivalent loading density would be 1.19 x 13.0 = 15.5 grains of powder.

If we use your value of 19.7 grain H2O capacity, then the difference in powder spaces is greater: 20.8 - 19.7 = 1.1 grain difference in case capacity, which comes off the powder space. So powder spaces become 14.5 - 1.1 = 13.4 and 12.2 -1.1 = 11.1, so 13.4 / 11.1 = 1.21, or 21% more capacity with the Speer bullet. That would make the loading density equal at 1.21 x 13.0 = 15.7 grains.

But, I think we are just making a numerical game of this speculation. What we need is some solid data on the combination of capacity AND case length for both the fired and resized conditions. Then we can see what loading density we are actually talking about.

Also, have you talked to Speer yet?

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