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Old March 30, 2010, 06:36 AM   #2
SL1
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Join Date: November 8, 2007
Posts: 2,001
Bullet length?

Just off the top of my head, I know that the Speer Gold Dots have an unusually blunt nose shape, while many FMJs for the 9mm have unusually long nose shapes. So, it seems plausible to me that the heavier bullet is still shorter than the lighter one. If so, then THIS heavier bullet leaves more space for the power than THIS lighter bullet when seated to THESE COLs.

And, it is possible that Hodgdon used different lots of Universal at different times to produce the data for these two bullets. That could mean that they used different lots of powder with significantly different burning rates.

Which brings-up the point that Hodgdon usually publishes the pressures of their loads, but you didn't provide those data in your post. Are these two loads producing the same peak pressure?

And, of course, there are always the possibilities of misprints.

Edit,

Now that I look at the data again, it seems that my first paragraph above makes the situation look more inexplicable instead of less. When I wrote that paragraph, I was thinking Speer GD was the heavier bullet and the Sierra FMJ was the lighter bullet. Still, I would have to know the length of the bullets to begin to try to figure this out. I am used to 125 grain GDs for the 357 Sig, which have almost no cavity. If the 124 grain GDs for the 9mm have a large cavity, then that could make them longer. Without doing a lot of research to find this info, I don't really KNOW. What I was attempting to do is give the OP some things to consider, so that HE can figure it out.

SL1

Last edited by SL1; March 30, 2010 at 11:23 AM.
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