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Old August 19, 2001, 08:29 PM   #1
CoyDog
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Hard-to-believe Velocity Readings

I ran some 300 Weatherby handloads across a friend's chronograph today and they produced some unbelievable velocities:

180 Scirocco, 84.5 grains IMR7828=3430 fps.
200 Partition, 82.0 grains IMR7828=3218 fps.

I couldn't detect any pressure signs, and my groups ranged from good to excellent. I find it hard to believe these velocities, since they should be impossible to attain in a 300 Wby. without terrible pressure problems. These readings are are 200 to 250 fps more than the Nosler reloading manual predicts. Nosler lists my 180 load as max, and the 200 load as 1 grain under max.

This is out of a Remington 700 w/ 24" barrel. We were shooting at 5500 feet altitude, if that has any bearing on the velocity or the chronograph. These were meticulously assembled loads, with each charge weighed individually.

My friend is blaming my powder scale, but I tend to think his chronograph is off. Anyone have any ideas about what might explain these velocity readings?
Thanks, CoyDog
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Old August 19, 2001, 08:58 PM   #2
Mal H
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I agree with you, those are some high velocities for the 300 Wby. And to make it even more out of line, they were produced out of a 24" barrel. Most 300 Wby loads are tested in 26" barrels.

Have you checked your scale with some check weights?

Can you test the chrono with a known velocity round. (A match grade .22LR such as Federal 900 A or B is a good calibration round.)

Was the chrono far enough away from the muzzle so the muzzle blast doesn't affect the readings? For that round, I would say 15 feet or more is sufficient.
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Old August 20, 2001, 07:39 AM   #3
WESHOOT2
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RETEST

and remember ".....but not always....."

It is certainly possible that your gun, with those exact loads, at that elevation and temperature, deliver the velocities you recorded.

I would, however, retest with the chrono at least 15 ft away....or a blast shield in front of your first screen....
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Old August 20, 2001, 11:31 AM   #4
CoyDog
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Thanks, guys. I think the mystery has been solved. My friend's chronograph was only 4-5 feet from the muzzle, and everything we shot over it registered high. Guess I'll have to get my own chrono and use it properly. Reminds me of the old adage: If you want something done right...

Good Shooting, CoyDog
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Old August 22, 2001, 06:57 AM   #5
WESHOOT2
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PACT ONE
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