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Surprise at the range yesterday.

Discussion in 'Ammunition & Reloading' started by 2ndtimer, May 28, 2013.

  1. 2ndtimer

    2ndtimer SE Washington state Active Member

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    I was out at my club range yesterday and was very surprised when I chronographed some loads in my 26" barrel Remington 700 SPS Varmint .223 Rem. I have chronographed 40 gr bullet handloads before with various bullets, Hornady V-Max, Z-Max, Sierra HP, Nosler Ballistic Tips with 27.5 gr of Ramshot TAC and they have generally run in the 3500 to 3650 fps range. When I chronographed the same load with the new Nosler Varmageddon 40 gr tipped bullet, the velocity ranged from 3300 to 3375 fps! I was startled enough to move the chronograph a little farther away from the bench to make sure that muzzle blast wasn't affecting my readings. I also chronographed some 40 gr Z-Max bullets with the same components and they were running in the more customary 3550fps range. I also had some 40 gr V-Maxes loaded with 26.5 gr of Accurate 2015 and they tripped the chronograph at over 3750 fps. (a more normal reading for that load, too.) Any ideas? Could the shorter flat based bullet make that big a difference? I have to recheck to see if I had loaded them with neck sized brass, as I know that, too, can reduce pressure and velocity. The primers were Remington 7 1/2's for the slow batch and Wolf 223's for the faster loads. I just don't recall seeing that big of a change for just the bullet in a given load. The point of impact was very similar for all 3 loads, and the accuracy of the Varmaggedon's was very good 4 touching, and 1 pulled. Just wondered if anyone had experienced anything similar. Thanks.
  2. misplacedtexan

    misplacedtexan Beaverton, OR Active Member

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    I've still yet to chrono anything, but I would imagine the different bullet led to a different amount of volume in the case at the same (or adjusted OAL) and that changed the pressures and velocities.

    but I'm just speculating.
  3. Miravox

    Miravox Seal Rock, Oregon, United States Member

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    A flat based bullet shouldn't make a difference until after it goes trans-sonic far down range. I agree that it's likely a matter of useable case volume.
  4. rodell

    rodell Newcastle, WA Active Member

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    Neck tension can definitely contribute to the variance. It is a question of where on the pressure curve the bullet pulls free.