Sig Kilo 2400ABS Drop Calculations

buzzy

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I'm hoping to get some feedback on the data I collected between a few ballistic apps. I have been using my G7 BR2 (2nd gen) rangefinder and have it dialed in pretty good with my rifle. I recently received a Sig Kilo2400ABS unit that I'm trying to calibrate. The FPS data below for the G7 is confirmed data at the range. I then calculated the other data on Shooter and Berger to complete the table. The only data that I manipulated was the FPS to get the MOA corrections to be accurate out to 1000 yards. Surprisingly the data for Shooter, G7 and Berger match up pretty well. The data from the Kilo is off a little and was wanting to see if this made sense to others and get your feedback.

As an FYI I'm shooting the Berger 195 grain elite using the G7 BC of .387. Using RL33 and this is a wildcat round using .338 Lapua brass necked down with CCI magnum primers. I did back calculate the density altitude to altitude to make sure the G7 and Kilo environmental conditions were reading the same and they were which was great to see.

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As you can see from the data the Kilo is consistently off by .2MOA up to about 700 yards. Then it matches up well with the other apps. I'm thinking it might be better to go back and recalculate the FPS on the Kilo to get the data to match up at the shorter ranges (assuming I can get them to match better) and keep in mind that anything over 700 I might be shooting .2 or so MOA off. I also have to get to the range, which is really hard to find a 1000 yard range near me, to confirm the Kilo data but since it matches my G7 that I have confirmed I figure I should be pretty close.

I have used a magnetospeed and chronographed my rounds at 3296 and the smith informed me that during load development he calculated 3295 FPS as well. However when at the range I had to crank up the FPS to get hits at the longer distances and with 3415 on the G7 I was good all the way to 975 yards.

Would love to hear feedback. Maybe I'm overthinking this and being off .2MOA is no big deal but I want to get this as accurate as I can. I would have thought the ABS would have matched up better with the other 3 apps but it's not. Thanks
 

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JakeSCH

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Interesting. Did you choose distances based items you ranged? If so, I would verify inclination. An inclination could explain the differences.

Pretty sure the ABS uses Litz's (aka Bergers) ballistic calculation.
 
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buzzy

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Interesting. Did you choose distances based items you ranged? If so, I would verify inclination. An inclination could explain the differences.

Pretty sure the ABS uses Litz's (aka Bergers) ballistic calculation.
Thanks. I ranged distances from a bench with no incline to take that specific variable out of the equation. And yes I think you are correct about the system. That’s why I find it interesting the Berger ballistic calculator is so different as they were both created by Litz.
 
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That seems like a pretty drastic velocity jump vs what your magnetospeed is reading also.
How many rounds down the barrel? Have you chronographed the load recently?
 
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buzzy

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That seems like a pretty drastic velocity jump vs what your magnetospeed is reading also.
How many rounds down the barrel? Have you chronographed the load recently?
I was wondering that as well but when I got the 3 programs to pretty much align on the drop I figured that was the correction needed to make the apps accurate in the real world for my ammo. I don’t know if others have seen this type of fluctuation with actual shooting conditions vs what a chrono has read.
 
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buzzy

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That seems like a pretty drastic velocity jump vs what your magnetospeed is reading also.
How many rounds down the barrel? Have you chronographed the load recently?
Forgot to answer one of your questions. Only 40 rounds down the barrel and last chronographed about 10 rounds ago.
 
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Forgot to answer one of your questions. Only 40 rounds down the barrel and last chronographed about 10 rounds ago.
In my experience Normally at about 120-150 rounds most barrels tend to speed up a little and settle in. I would keep shooting and verifying your results on paper as well as getting some rounds down the barrel.
 
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Would love to hear feedback. Maybe I'm overthinking this and being off .2MOA is no big deal but I want to get this as accurate as I can. I would have thought the ABS would have matched up better with the other 3 apps but it's not. Thanks [/QUOTE said:
.2 MOA is no big deal, until you miss. The solution is not to fudge FPS. Something else is a problem.

I had the exact differential you are experiencing, and many others have as well if you research this. Verified drop calcs and dope will line up on other programs, but not on the Kilo. A few things that made the difference for me and now have a Kilo that is flawless:

#1 - Wind: Early on in my ignorance, I did not input accurate (or any) wind speed and direction. The AB calculator needs this environmental information for an accurate trajectory calc.
#2 - Temperature: my internal temp sensor was failed. The incorrect temperature being read and inputted by the Kilo showed 160°F, which also messed with pressure and inputted an incorrect attitude reading of over 2100ft when at 445ft. The 160° F reading is the tell-tale kiss of death that the sensor has failed.
#3 - Target direction Azimuth/Coriolis: make sure you're pointing the Kilo in the same plane as your shot trajectory.

Now, before I head out to use the Kilo, I step outside the day before and verify the Kilo's environmental accuracy on the HUD and Environment screens against either my phones internal barometer or with a Kestrel station. I know this sounds like a lot or high-maintenance, but the sensors are very sensitive and the AB calculator is no joke in these, and small differences make or break your 1st shot success. Professional and military teams are always verifying equipment readiness prior to use, so should we. Once these systems checks, environment and wind readings were implemented everytime like clockwork, the Kilo has performed better at long range than my G7 and onpoint with a Terrapin.
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khuber84

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Running a 250y zero is the quickest way to throw errors into your system once weather changes from the weather you zerod in. Best way to run a distanced zero: zero your rifles at 100y, then dial whatever come up it takes for your desired zero. This takes about 90% atmospherics out of the equation. Do you have any zero weather installed into the kilo data that may be giving less drop? A R to L or head wind will cause less drop. Can you shoot the difference of a 1/4 or less moa at distance.
 
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buzzy

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Running a 250y zero is the quickest way to throw errors into your system once weather changes from the weather you zerod in. Best way to run a distanced zero: zero your rifles at 100y, then dial whatever come up it takes for your desired zero. This takes about 90% atmospherics out of the equation. Do you have any zero weather installed into the kilo data that may be giving less drop? A R to L or head wind will cause less drop. Can you shoot the difference of a 1/4 or less moa at distance.
Thanks. The reason I have a 250 zero is I’m shooting an extremely flat shooting bullet. With. 250 zero I’m able to shoot anything out to 300 yards without needing to adjust my scope.

I may have to explore going back to a 100 yard zero to see if the curve can match up better. Thanks
 

khuber84

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Thanks. The reason I have a 250 zero is I’m shooting an extremely flat shooting bullet. With. 250 zero I’m able to shoot anything out to 300 yards without needing to adjust my scope.

I may have to explore going back to a 100 yard zero to see if the curve can match up better. Thanks
I'm not saying it's the reason your dope isn't all true but here's a scenario: I live at 4k foot elevation, say I zero my rifle on an 80° day in August where DA is around 5700' at 250y. Now hunting season I head out to Eastern MT to hunt deer/antelope on the family farm. It's now 1900' elevation and 30° and DA is now 1200'. A 100y zero will be affected a lot less than a 250y from these atmospheric charges. I know a good/smart shooter would check zero at hunting location, but you'd be surprised the number of folks who don't. This is my reasoning for suggesting 100y zero. Another thing to test, temp sensativity of your Rl33 load. Shoot some rounds that are as warm as you can get them, and then freeze some in a hydro flask for 2-3 days in deep freeze. As quickly as you can, wipe any frost/condensation off the rounds and run them across your chrono. Rl33 is known to be quite temp sensative. You may see as much as a 80fps drop from 80° to 20° temps.
 

JakeSCH

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@buzzy following up with this...do you have a default wind values on your sig? In my sig2400abs, I usually keep a 10 MPH windspeed from 9 o'clock and use that for scale for actual wind speed.

Sig accounts for the aerodynamic jump from crosswind, so you would get different tuned profiles / muzzle velocities depending if you had a cross wind from 3 o'clock or 9 o'clock...
 
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buzzy

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@buzzy following up with this...do you have a default wind values on your sig? In my sig2400abs, I usually keep a 10 MPH windspeed from 9 o'clock and use that for scale for actual wind speed.

Sig accounts for the aerodynamic jump from crosswind, so you would get different tuned profiles / muzzle velocities depending if you had a cross wind from 3 o'clock or 9 o'clock...
Yep and I do the same as you but from 3:00
 

JakeSCH

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Yep and I do the same as you but from 3:00

So if you look, at 3 o'clock wind gives it a jump...less drop. I can almost guarantee that is why they don't line up. Change that wind speed and it will give you results that align with the others.
 
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buzzy

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Thanks and I’ll check that out. Although I don’t understand why if you have a wind value entered at 3 or 9. I would think it would be the same for these 2 positions.
 

JakeSCH

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Thanks and I’ll check that out. Although I don’t understand why if you have a wind value entered at 3 or 9. I would think it would be the same for these 2 positions.

Aerodynamic jump. The cross wind creates lift from 3 o'clock and reduces lift from 9 o'clock.

It has to do with the cross with and the spin of the rifling...if your rifling was spun in the opposite direction than the jump would be opposite
 
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buzzy

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Aerodynamic jump. The cross wind creates lift from 3 o'clock and reduces lift from 9 o'clock.

It has to do with the cross with and the spin of the rifling...if your rifling was spun in the opposite direction than the jump would be opposite
So what do you set the wind for if there is no wind? My understanding is you need to have a value in the system.

Thanks
 
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