Help Understanding Ballistic Turret

[trogers861]

Hi All,
I recently acquired a new 6.5CM and put a Leupold VX6HD 3-18x44 on it. I am shooting Barnes Vor-TX LR 127g ammo. This is my first time using a ballistic/tactical turret.

Trajectory on this round is +1.7@100, 0@200, -7.5@300, -21.6@400, -43.5@500.

I didn't do any research ahead of time and made a dumb assumption and just thought with the turret, I should zero it at 100 yards. I am reading now that I should have zeroed at 200 yards.

Questions:
1a. If I would have sited in at 200yards, when shooting at 100 yards, my impact would be 1.7" high, correct?

1b. I know this really doesn't matter at 100yards in relation to kill zone on an animal--but how would I compensate for this? There is no 'down' option on the elevation on the turret--so would I just result to the old fashioned 1.7" hold under, correct? I'm sure its faulty logic, but this is why I was thinking I should zero it at 100 yards.

2. If I want to keep it zeroed at 100 yards, what are my elevation adjustments for 200, 300, 400 and 500? My mind exploded when I tried to figure this out even though I know it has to be relatively simple. I think all I have to do is subtract 1.7" from the trajectory at 200, 300, 400 and 500. So it would be -1.7@200, -9.2@300, -23.3@400 and -45.2@500. Sound or faulty logic?

3. Are there any strong reasons to change my zero at this point?

Thanks everyone!

 

[Novahunter]

1. Always zero at 100 yards.
2. Stop thinking in inches. Is your scope MOA or MIL based? Learn the angular measurements of your scope, and the linear inches of drop at specifc yardages becomes a moot point.

 

[cmahoney]

Download this app or another similar one, then input the data.

‎GeoBallistics

‎About This App: GeoBallistics is a mobile app available for iOS devices and is compatible with Vortex Razor HD 4000 GB and Impact 4000 devices. The app allows users the freedom to build and create unlimited rifle profiles, connect with weather-hardware for onsite atmospherics...

apps.apple.com

Sent from my iPhone using Tapatalk

 

[Keep On]

In a hunting situation I wouldn't worry about holding under at 100 yds, crosshair in middle of vitals, let out breath and squeeze.
I still zero for 200 with a tactical scope, out to 300 no need to adjust the turret. 6-8" hold over for 300, no meessing around with dials needed. Only dial for shots past 300.
If you want a 200 yd zero, just set 100 yd target for 1.7" high. And as recommended get a ballistics ap and watch a few YouTube videos on moa and mil.

 

[Wrench]

Trusting the ammo box, mfr turret corrections and no environmental input is a recipe for disaster beyond 7 or 8 minutes.

You could come up 7 clicks and reset your turret and hope for the best.....or shoot to verify your anticipated conditions and build some dope.

 

[Outdoorsman12b]

You can zero at whatever range you want. Your way overthinking. Don’t order that ballistic turret until you verify your velocity.

 

[SomeJackassOnAForum]

Download this app or another similar one, then input the data.

‎GeoBallistics

‎About This App: GeoBallistics is a mobile app available for iOS devices and is compatible with Vortex Razor HD 4000 GB and Impact 4000 devices. The app allows users the freedom to build and create unlimited rifle profiles, connect with weather-hardware for onsite atmospherics...

apps.apple.com

Sent from my iPhone using Tapatalk

1. Get a Ballistic Program
2. Input your data. Use the manufacturer ballistic data as a starting point. (https://www.barnesbullets.com/product/vor-tx-long-range/)
   1. Box Muzzle Velocity is 2850, this is a reasonable place to start if you don't have a chronograph, but it's better to borrow a chrono than shoot box data.
   2. Box G1 BC is .468
3. Shoot using the data from the app and make corrections if necessary. Ballistic apps like Strelok Pro will have a "truing" function, but this can be done manually.
   1. If you're impacting low/high at all points, lower/raise your muzzle velocity until your corrections match real world experience (10-25 FPS at a time)
   2. If you're hitting well out to 600 yds but are then low/high, lower/raise your ballistic coefficient until your corrections match real world experience. (0.005 BC at a time is a good start)

Ballistics aren't complicated. Your bullet is slowing down horizontally due to drag, and accelerating downward due to gravity. The drops in inches on the box are very unhelpful because they were taken at a given altitude for a given rifle, with a given barrel length/twist rate/rifling that you probably don't exactly have. Spending a few minutes playing with a ballistic program will make you better understand what your bullet is doing!

 

[kevin11mee]

It doesn't really matter if you choose a 100 yard or 200 yard zero, it's personal preference. The advantage of a 100 yard zero is that it is easier to get more exact and easier to check your zero before a hunt at 100 yards rather than 200.