two Kestrel questions, 5700 E/AB +Link

[newgunguy3]

#1 - when you turn on the Kestrel, during the splash screens you start to get a battery capacity reading. It disappears once the splash screens are finished. I know it's not 100% accurate because I've put a new battery in and gotten readings below 100%. How can you see what the battery capacity is so you can decide pre-emptivily to change the battery rather than waiting until it dies . . . at the most inconvenient time?

#2 how does the kestrel know, or guess, what the environmental conditions are/were when a gun was zero'ed so it can make accurate recommendations going forward? Real life use case -- I'm at a class, first couple of strings of fire at 100 yds are to confirm 0. Used Kestreal in weather mode to get environmentals for my records. But my gun is clean so needs some rounds to dirty the barrel before it settles in for a confirmed 0. We moved to a different distances for the rest of the day. Based on shot results at these other distances I make some scope adjustments to set zero. Next day, check at 100 yds, perfect. Day 3, it's FREEZING. DA is almost 2k different than conditions when I set scope zero on day one and confirmed on day 2. The kestrel gives me a negative elevation to compensate for the change in conditions. How did it know that I made a final O at (say) 4000 DA and its now 2000 DA so do x for adjustment? Or for that matter that I zero'ed at 2000DA and it's now 4000 DA and need to make other adjustments?

it's not in the gun profile. It's not in the profile on Kestrel Link, how does it know what the zero DA is??????

Thanks

 

[_Windrider_]

To answer number 2 first, zero environmental conditions are irrelevant for a 100 yd zero. The zero conditions are for distances other than 100. People using 1000 yd zeros are using more robust BC’s and using kestrel strictly for environmental, I think that’s why it isn’t included.

as for the batteries, watch the splash screen, change when you are no longer comfortable with what you see. Use lithium batteries. Also if you go in the settings it’s in there. I don't have mine with me but it even knows whether you have alkaline or lithium batteries.

 

[newgunguy3]

Thanks for the reply. Interesting that you say conditions don't matter for 100 yards 0's. In my real life example, I zero'd at 4000 DA. This morning it was close to 2000DA. I didn't consult the kestel before shooting and all my shows were .1 Mil+ high. I was puzzled since I had confirmed 0 the previous day at conditions almost identical to when I set the scope.

I turned on the kestrel, updated environment, and low and behold for my 100 yd target distance it was telling me to dial .15 Mil Down, exactly what my target was telling me. If weather at 100 doesn't matter why is the kestrel giving me an accurate firing solution based on the current, freezing, conditions? It had to know the DAs were different (zero conditions and now). But how?

 

[Teamworksetd]

I have experienced the same thing with the Kestrel where it gave me a .13 mil down solution at 100 yds. I have always thought that it doesnt matter at 100yds but that was not my experience in this situation. Looking forward to hearing the answer.

 

[Diver160651]

Thanks for the reply. Interesting that you say conditions don't matter for 100 yards 0's. In my real life example, I zero'd at 4000 DA. This morning it was close to 2000DA. I didn't consult the kestel before shooting and all my shows were .1 Mil+ high. I was puzzled since I had confirmed 0 the previous day at conditions almost identical to when I set the scope.

I turned on the kestrel, updated environment, and low and behold for my 100 yd target distance it was telling me to dial .15 Mil Down, exactly what my target was telling me. If weather at 100 doesn't matter why is the kestrel giving me an accurate firing solution based on the current, freezing, conditions? It had to know the DAs were different (zero conditions and now). But how?

This offset has more to do with your clothing or you, than the DA. Turn off Aj etc..

I'll print out a 110-degree swing at 100 yards, using the muzzle as pure muzzle drop. ie zeroed at the muzzle. The delta is rounded so it's less than <0.1" which's still a single bullet hole hardly detectable or even relevant for that matter. Note that Drop is what the bullet is doing, the path is what we dial. I included 1000 yards as a reference point so you can indeed see DA has an impact at long range, but other than an academic, not in play for our fast high bc rifle rounds.

DIST yards	TRACK - 1 Wyoming House 110 degrees MRAD	TRACK - 2 Wyoming House 0 degrees MRAD	TRACK - 3 Sea level CA House La Honda 70 degrees MRAD	TRACK - 4 Wyoming House 110 degrees inches	TRACK - 5 Wyoming House 0 degrees inches	TRACK - 6 Sea level CA House La Honda 70 inches
100 DROP	-0.5	-0.5	-0.5	-1.84	-1.87	1.88
1000 PATH	6.0	6.6	7.0	-203.4	-223.9	-234.7
1000 DROP	7.0	7.7	8.0	-240.1	-260.6	-270.4

 

[newgunguy3]

Thank you for the information you posted. I’ll digest it.

I understand and agree the DA changes are more pronounced at greater distances. But shouldn’t the Kestrel know “where” a gun was zero’ed (DA)? For an outlandish example, you zero at sea level at distance X then climb half way up Mt. Everest. Shooting at that same distance will have a different POI won’t it? The kestrel needs to know the difference between 0 DA and shooting DA to make the correct firing solution for any distance, right?This one is easy because most solutions assume sea level start. But turn it around, zero on Mt. Everest then go to Death Valley.

In my mind it doesn’t seem to work. zeroing a scope based on POI on Everest will / should be different than POI in Death Valle, right? If so, then the Kestrel needs to know the zero conditions. I realize if you zero then shoot at sea level or zero then shoot on Everest you’re working off the same baseline. I’m curious about when the baseline and current are different.

again, my appreciation for helping me learn and understand. Thanks.

 

[_Windrider_]

Thank you for the information you posted. I’ll digest it.

I understand and agree the DA changes are more pronounced at greater distances. But shouldn’t the Kestrel know “where” a gun was zero’ed (DA)? For an outlandish example, you zero at sea level at distance X then climb half way up Mt. Everest. Shooting at that same distance will have a different POI won’t it? The kestrel needs to know the difference between 0 DA and shooting DA to make the correct firing solution for any distance, right?This one is easy because most solutions assume sea level start. But turn it around, zero on Mt. Everest then go to Death Valley.

In my mind it doesn’t seem to work. zeroing a scope based on POI on Everest will / should be different than POI in Death Valle, right? If so, then the Kestrel needs to know the zero conditions. I realize if you zero then shoot at sea level or zero then shoot on Everest you’re working off the same baseline. I’m curious about when the baseline and current are different.

again, my appreciation for helping me learn and understand. Thanks.

The only thing that will effect your zero at 100 yds is velocity difference. If I zeroed at 100 degrees and am now shooting at 20 degrees, my velocity is slower. Guaranteed. Is it enough to matter? Maybe, maybe not. But I can confirm my zero update the offset in the app if I’m 1/4” low and drive on. No need to re Zero.

let’s see what they guy who writes the software for AB says. @DocUSMCRetired what say you.

 

[Diver160651]

Thank you for the information you posted. I’ll digest it.

I understand and agree the DA changes are more pronounced at greater distances. But shouldn’t the Kestrel know “where” a gun was zero’ed (DA)? For an outlandish example, you zero at sea level at distance X then climb half way up Mt. Everest. Shooting at that same distance will have a different POI won’t it? The kestrel needs to know the difference between 0 DA and shooting DA to make the correct firing solution for any distance, right?This one is easy because most solutions assume sea level start. But turn it around, zero on Mt. Everest then go to Death Valley.

In my mind it doesn’t seem to work. zeroing a scope based on POI on Everest will / should be different than POI in Death Valle, right? If so, then the Kestrel needs to know the zero conditions. I realize if you zero then shoot at sea level or zero then shoot on Everest you’re working off the same baseline. I’m curious about when the baseline and current are different.

again, my appreciation for helping me learn and understand. Thanks.

Ok, let restate what you said in a simpler way. instead of using Death Valley and Everest.

1. you have a DA delta of only 2,000'​

2. you said you need .1mil or .36" to reestablish our zero.​

​

I gave you an example of over 12,500' DA delta with less drop differential than you can adjust for. I really think that covers most anyone's realistic usage parameters without using airline cruising altitude.​

Here it is in DA -- BTW stop using DA it will over complicate our head. Use station pressure.

Here is the above restated in DA. IN both these example the gravity drop is rounded to -1.9" on my 7mm @ 100 (run on Coldboare & AB analytics)

Ca House​

• temperature: 70 deg f
• uncorrected barometer: 29.920 Hg
• humidity: 50 %
• vapor pressure: 0.739 Hg
• dew point: 50.478 deg f
• grains: 54.5
• air density: 96.899 %
• density altitude: 1,074.379 ft

​

Wyoming house​

• temperature: 110 deg f
• uncorrected barometer: 22.5 Hg
• humidity: 50 %
• vapor pressure: 2.599 Hg
• dew point: 86.792 deg f
• grains: 262.0
• air density: 65.823 %
• density altitude: 13,636.917 ft

Why is this so?

Drop is a function of gravity exposure (time). Gravity is acting on the bullet constantly and pulling it down immediately as it leaves the barrel.
Drag is a far more complicated mix of speed, shape and affected by air density. The caveat with drag is that it takes time to effect change to actually slow the bullet.

The 100y TOF is 0.099 seconds with a velocity of drag influenced FPS of 2942.8 vs TOF of 0.099 but drag (DA) influence a higher velocity of 2984.8. (you need to note that the barrel node is the same for both, while certainly is some TOF difference it's too small to deal with). Yes, the calculators are tracking and round the math, so the true gravity drop might be reported as a delta of .04", I'm mean that's not even 1/2 a 1/10th of an inch or 10x smaller than you can adjust your mrad turret. If you shot a group that tight you might assume all but 1 bullet grenaded in-flight LOL.

Since gravity needs time (seen as distance in our shots) to create drop and because the TOF is so close to each other at 100y, we see no perceptible elevation change at 100 yards. This is one of the main reasons 100 yards is the preferred number over something like some hunter's 300-yard zero's and some BR guys 600+ yard zeros; plus it's all holdovers, not a mix.

If I took my same fast 7m and use a 300 yard zero (3x+ more time for drag to work) I would need to enable zero conditions on the solver as the above example would result in -18.1" drop vs 17.6" drop or adjust .1mil for the 300y zero shift. Slower and lower BC bullets will have more drastic results, as would the guys with 600+ yard zeros.

Did you turn off AJ as suggested and zero the wind?

So, I answered your external ballistic question- the offset is NOT from the DA delta; however, if it's not from how you mount the gun, how you load the gun or the extra jacket, it is possible you have something mechanical (internal ballistics/node) going on, but the calculator if set correctly should not be predicting that.

Food for thought:
How many people have you seen at a public range put their gun in the safe for a while and come back out to re-zero, having to make adjustments? Is possible a few feet in DA is the issue or maybe gremlins unmounting and remounting their scopes in the safe? No, it's how they are managing the recoil and sight picture slightly different each time.

BTW my AB products do not give me different zeros settings when set up properly.

Last takeaway - You never know when you tech is going to bite it. Always carry a drop print, the best strategy is to look at the entire trend of the drop and where those numbers aren't bouncing back and forth. Don't get too focused on the individual drop numbers even with 20 almost nothing and with 40 degrees of temp shift out to 600 or so. The calculators are rounding, so what might look like a change is sometimes only a shift between 2.34mils and 2.35mils, reported as 2.3 and 2.4 or whatever.

Here is an example of my hunting card from the last Elk Hunt, printed on my sidewinder. 3x5 2 sided folded over. The wind is shown in FV and only at the wind brakes.

I took the time to write out all this stuff in the hopes it helps you see and investigate the bigger picture rather than just get buried in the device.

 

[Dthomas3523]

I mean this in the least offensive way. But no one shoots consistent enough and conditions the kestrel can’t account for (lighting, recoil management, etc etc) to say your .1 or .2 difference is a change in zero due to environmental conditions the kestrel does track.

I.E. your 100yd zero from one side of the country to the next doesn’t change due to measurable environmentals.