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Rookie Mistake

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Working up some new Barnes TTSX loads for the 300 Weatherby 

Lubed,  sized, trimmed, chamfered, uniformed the flash hole sorted by headstamp loaded up a ladder and went to the range. 

1st group varied over 50fps, second group not good either, 3rd or 4th group max sammi had 1st 3 within 5fps spread and last 2 almost 100fps slower.

Same with the max + .5gr batch, WTFO?

Luckily last 2 batches were 3 good ones in a row and 2 slow, got me thinking...

Looking at the brass when I got home I had mixed Weatherby R-P 300 Mag and Weatherby 300 Mag brass. 

Case volume 6.41 cc h20 vs 6.67cc h20, dry weight almost 15 grains more with the R-P.

Looking back at my data it looks like R-P with 79 gr H4350 was close to the same velocity as Weatherby with 80.5, assuming all the slow ones were the Wheatherby 

I checked dry weight on a few Normas, and a couple other brands I had 1 or 2 of, all close to the R-P.

Weatherby brass has more volume then the rest. 

Got to sharpen the eyesight at the reloading bench before sending 25 bucks worth of reloading components down range at 3400fps!


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That's not a rookie mistake, Al - that's pretty far up there in the advanced stages of reloading, man, with what you're working with.  Even 100fps slower is pretty damn impressive! :hail:

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Thanks for the vote of confidence!

I like to see SD's less then 10 for rifle,  but if you play with a dope sheet with magnum rifle velocities it takes a lot more then that before you could even measure the difference at 500 yards.

Revolvers are the worse offenders, forcing cone gap blowing pressure off, un-even cylinders, if I get an SD in the under 30 range with a magnum revolver load that's an accomplishment.  

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