Originally Posted by Riflecrank
Sir Tony,

Nov. 1955 published lab data on the factory 500-gr FMJ showed 2087 fps instrumental in a 25" barrel.
See bottom line of load data below (from NRA, Gen. Hatcher's RIFLEMAN article):

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My 2080 fps in a 25" Shilen barrel was corrected to MV.
But I think the Shilen groove diameter might have been 0.4585" instead of the tighter original 0.4582".
And my temp was 50*F instead of 76*F.
Just about identical results considering those differences in test bed, after 64 years on the shelf for your 1957 vintage.
Buy a donkey for taking such good care of that factory ammo.

Inspirational material for Sir Jerry:

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Sir Ron,
That's great informational Load Data on the 458 WM from 1955 proven tried and true.
26 degrees difference in temps. and not much difference in results. That in itself is interesting Data.
Adding onto the Barn, making more room for Donkeys! LOL!

Last edited by HunterShooter58; 05/28/22.
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