Why does the Speer manual....


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Das1
November 18, 2007, 02:02 AM
list different loads for .357 mag with 296 and H110 powder? They vary quite a bit , too.
For example - loads listed for a 140 g bullet

296 - 17g,1327fps 18g,1367fps

H110 - 16.2,1323fps 17.2,1352fps

interesting , since a trip to the hodgdon website confirms that these two powders ARE EXACTLY THE SAME POWDER.

(H110 , 296 - 17.1g,1597fps 19g,1762fps)

I understand that the velocity difference between the Hodgden and Speer data could be due to different test barrel length. (Speer manual lists no test pressures , so can't compare there.)

Comments?




Kind of makes me question how they come up with their data. (think I'll use the Hodgdon recepies

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jhansman
November 18, 2007, 02:21 AM
Hodgdon's site lists virtually the same data for both powders for the Hornady 140gr. XTP (17-19gr.). I tend to go with their data, as manuals these days vary so much for bullet/powder combos.

achildofthesky
November 18, 2007, 10:52 AM
Some of their loads are a HUGELY different from bullet manufacturers and other sources. Some of their starting loads are above the max loads listed from bullet co. loads! I have not had a problem with it other than being surprised at the comparative power differential between the "lesser" loadings of the bullet co's recipes. My base 45-70 loads for my 1895 are definately heavier than expected (yes, I used the correct section for Marlin lever guns).

Be safe and double check your info and then check it again...

Patty

rbernie
November 18, 2007, 10:57 AM
Probably because the loads were worked up at different times with different folk and different circumstances.

They don't re-test every load for every edition of the manual - they generally republish the old data and add new powders/bullets as needed unless they have some compelling to re-test the old data.

Ol` Joe
November 18, 2007, 11:55 AM
The lot of 296 wasn`t from the same batch as the lot of H110. The variation in the lot of powder used is the cause for a lot of the difference in various manuals, along with the bullet used. This is a big part of the reason for suggesting starting low and working up. You don`y know if your batch is a fast or slow one compared to the lot used to develope the data.
(I know, don`t reduce H110/W296 from the book min. Still, look at the reduction from book max to min in other manuals between the two, Speers is 16.2-18.0 grs. Hummmm, 10% of 18 gr is 1.8gr or 90% = 16.2gr.)

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