Trying to determine cartridge Velocity ... data seems odd

[philcox]

Trying to determine Velocity on my Barnes LRX Ammo. Using the VOR-TX 129gr LR in .270. Off the Barnes site, says 3140. I bought a "Caldwell Ballistic Precision Chronograph" to do the measurement. I have been out 2 times, and giving some time between shots, here is what I was getting from the Chrono:

• Day 1
  • 3254
  • 3215
  • 3215
  • 3304
• Day 2
  • 3014
  • 3010
  • 2984
  • 3033
  • 3097
  • 3108
  • 3194
  • 3182
  • 3091

Couple Questions:

1. I think "Day 1" might be have been affected be shade. Does that make sense?
2. Does the deviation on "Day 2" seem reasonable for a factory load? I tried to wait a good bit of time between shots to let barrel cool
3. Is the Cladwell something that I can count on?
4. If the Caldwell is a good piece, then is there a "way I need to use it" so it gives the most accurate reading?

Thanks,

Phil

 

[manitou1]

I changed to a magnetospeed and get more consistency. For some reason, I always had issues with the conventional shoot through chronies, even when using sun shades, shooting at correct times, etc.

 

[Brendan]

I honestly don't think you can count on optical chronos like the caldwell.

Best way to use them is keep them completely shaded - use on a cloudy day, with a cover over the top for consistency. I have one, only thing I use it for is archery - in my basement with a light kit.

 

[WCB]

Some of this could depend on how you had it set up...

distance: were you consistance from day 1 to day 2, is it set at similar distance as factory testing

shielding: If set up close you may want to put a piece of paper in front of the chrono...this blocks and eradicate triggering by gasses coming our from the barrel

Overall the box numbers are shot in test barrels I would say the 2nd day makes more sense on a general ballpark of what I would expect presuming you are probably shooting a barrel shorter than 24"

If those are the real numbers and the chrono was working as designed. Throw that ammo in the trash. Range is WAY outta whack and is no way typical of quality factory ammo.

 

[Rich M]

Was one day hotter than the other? Cartridges in the sun?

Most stuff I've seen is that the Caldwell and magnetospeed report pretty close. This is from comparison writeups.

 

[philcox]

Thx all for the input. I will try the "keep in the shade part next time.

 

[Wrench]

Another method of validation is to shoot 100, 300, 500 and use your results to validate.

 

[TauPhi111]

So I load lots of barnes and also have the same chrono. First off I will say if you are loading straight from Barnes load data, I have found their data and velocities to be spot on with what I get. Second, with those chronos, they are adversely affected when in direct sun, not in shade, so I'd say the day it was in the shade was more accurate. It is hard to say how direct sun affects the readings. Some days I just get lots of errors. The other day I was shooting some 45 ACP and it was telling me they were hitting 1200 FPS...well my pistol and my hands are still intact so that was obviously wrong. You definitely need to be paying attention to light, distance from muzzle, and other things people have said. Also be sure you have fresh batteries in the thing.