Prime 6.5 Creedmoor published BC vs actual BC

Oct 21, 2013
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The Frozen Tundra
#1
I went out today to true up my Kestrel with what I'm seeing in real life. Unfortunately I only have a 567 yard range to true things up on at the moment so I have to make do with what I have. I'd have like to run out in 100 yard increments however the 200-400 lane was being occupied by people doing mag dumps on their ARs for well over an hour. I'll have to get out and go from 200-567 in 100 yard increments another day.

The published G7 BC for the Prime Norma 130 Diamond is 0.295. With that BC and my environmentals for today, my Kestrel was showing 2.66 Mils of elevation and anywhere from 0.05 Mils to 0.2 Mils for wind holds. My actual elevation is 2.5 Mils. I have to adjust my G7 to .360 to get things to line up with what I'm seeing in real life. Has anyone else seen this discrepancy in the published BC versus the actual BC on Prime?

Firearm:
AI AXMC
26" AINA 6.5 Creedmoor barrel
TBAC Ultra 7
NF ATACR 7-35x56 Mil-C
Round count: 140

Ammo:
Prime 6.5 Creedmoor
Velocity: 2948fps avg.

Environmentals:
Temp: 75.2 F
Station Pressure: 29.20
Humidity: 49%
DA: 2050


Maybe @Lowlight or someone else that shooting Prime more often than I can chime in with some insight?
 

Lowlight

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Apr 12, 2001
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#5
With that software you adjust either MV or BC, I have found adjusting the BC is better, although your range is a bit short, anything will work you are not shooting far enough to matter.

Being off .1 Mil at 600 is only 2" off, I am sure you are not holding a 2" group at 600 yards, so let's say you shoot 1/2 MOA that is 3" you are inside the group size, in other words, you are splitting hairs on both range and elevation.

Using AB with my 136gr load when I did the BC at 800 yards it was listed as .545 and I ended up using .588 to line it up. Fixed a lot of shortcomings from the software by using a better BC vs changing the MV by 100fps
 
Oct 21, 2013
497
48
28
The Frozen Tundra
#6
With that software you adjust either MV or BC, I have found adjusting the BC is better, although your range is a bit short, anything will work you are not shooting far enough to matter.

Being off .1 Mil at 600 is only 2" off, I am sure you are not holding a 2" group at 600 yards, so let's say you shoot 1/2 MOA that is 3" you are inside the group size, in other words, you are splitting hairs on both range and elevation.

Using AB with my 136gr load when I did the BC at 800 yards it was listed as .545 and I ended up using .588 to line it up. Fixed a lot of shortcomings from the software by using a better BC vs changing the MV by 100fps
I did make it a point to avoid touching my MV in the Kestrel. No point in having a Magnetospeed if I'm not going to trust what it's telling me.
 

Lowlight

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Base of the Rockies
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#7
That has always been my issue too

We have much better Chronographs that guys are buying, then their "App" asks them to change the MV by a wide margin, so the question becomes, what is the point of even owning a Chronograph is you are just gonna change it. Between LabRadar and MagnetoSpeed why are we changing these numbers so significantly?

Might as well SWAG it regarding your MV, figure out the drop and then true the software and let it pick a new MV for you. it's gonna ask for that anyway.
 
Jun 26, 2012
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N. Carolina
#8
I did make it a point to avoid touching my MV in the Kestrel. No point in having a Magnetospeed if I'm not going to trust what it's telling me.
at some point you will have to adjust both. what lowlight is saying do the BC first and then maybe a slight tweak of the MV to bring it in line, ive never done more than half of my ES (which about covers the margin of error in the chrono...i use a MS and Labradar).
 
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