Barnes LRX True BC?

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logan1080

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So I have worked up a sub MOA load for my 300wsm using a 175 grain LRX, 63.9 grains H4350, 24” barrel. I have a cheap Shooting Chrony that I have been using on every shot fired throughout development. This particular recipe is always around 3010 to 3040 FPS depending on the day. Yesterday it was around 3015 while I was shooting at different ranges to develop my dope card. I took my true bullet drop from 275, 375 and 500 yards and applied this to the Burris Ballistic calculator to get info for my Burris scope. Well when I trued in the velocity based on actual drop, it says I’m at 2957 FPS, or if I true it to BC it says I’m at .297. Using the .297 is giving me the most accurate (bang on) result when compared to actual drops on the Hornady Ballistic app.

Barnes advertises this bullet at 0.508 G1 BC. Has anyone else trued in the BC on these bullets and found they are way out?
 
TheSil3nce said:
Applied Ballistics CDM gives me a G7 of 0.247 and a G1 of 0.482

Give me your full details and I will run the numbers through the app
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3015 FPS
Altitude 1800’
temp 10 degrees C
Humidity 6%
Pressure 29.7 inhg
275 yards 12” drop
375 yards 24” drop
500 yards 44” drop.
 
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TheSil3nce said:
Hope this helps
Click to expand...
Yeah the tables don’t measure the same as real world drop so I suspect the BC on the LRX is over stated. Found an error where my Burris Signature HD is not dialing properly though. 44” average drop today at 500 = 8.8 MOA but the scope actually required 11.5 MOA to compensate. This was part of the confusion.
 
I used the Custom Drag Model from applied ballistics, sometimes the app is spot on, like with my blaser r8, but with my AI rifle, i have to validate everyload.

Go figure haha
 
BearClan said:
For what it’s worth, to my knowledge, only Hornady and Barnes use Doppler radar to verify their’s BCs, meaning theoretically, they would be publishing the most accurate BCs.
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I'm not sure if they're the only one these days but I do remember listening to the Hornady podcast where they mentioned that when Hornady got theirs, only Barnes had one at the time.
 
You zero could be lower than you realize

Based on 100y retained velocity on the Labradar, the 175gr LRX has a G1 of .505 in my 300wm
 
Sierra Edition V - 5th Printing Manual - apparently they found that B.C. will change with velocity in air - so I see some of their bullets have as many as 4 B.C. values listed - depends on the velocity that the bullet is going - so likely have highest velocity at muzzle - is one B.C. value, then over range it will drop down in velocity and therefore B.C. value will change. I suspect Sierra bullet guys might know something about bullets in flight. As if other makers or other customers want to "dumb it down" to one value, in all cases. Maybe can do so if a range to target is fixed, but if Sierra is correct, I do not understand how one number can represent the bullet's B.C., over multiple ranges.

In other words, Sierra seems to say there will be a B.C. value for a 200 yard shot, but a different B.C. value for a 500 yard shot. Same bullet. Same muzzle velocity.
 
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logan1080 said:
Barnes advertises this bullet at 0.508 G1 BC. Has anyone else trued in the BC on these bullets and found they are way out?
Click to expand...
First, I would suggest using G7 BC, these are boat tails.

Second, for accurate BC with a good sample size you can use a LabRadar V1 plus this online tool: https://bc.geladen.ch/labrabaco/labrabaco.html , or you can wait and see what the LabRadar LX does when the upcoming firmware upgrade includes BC.
 
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