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Hi

I have a quick question on the applied ballistics app

I have inputed all the data as required but am finding an inconsistency between by zero distance (111 yards - short Siberia) and the point at which the output shows zero vertical correction - I am getting the round going through zero at about 65 yards and then back through at 145 yards - I have out the right scope height in 

 

any ideas on where I am going wrong

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other question - I would love to print out some good tables to about 1200 yards for the 6.5CM - any suggestions on programmes - presumably from the PC or Mac that can do this well?

thank you again

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To question one - that was interesting

the 10 mph 90 degree wind was giving me at .4 moa lift at my original zero - when I set the wind to zero the clicks and zero coincided - I clearly have much to learn

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I have it on my iPad.

If you just click on tables it will give you all your come ups to whatever distance you have programmed.I simply then just email myself at work,print it on some expensive paper and laminate them 

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Hobbit,you might  have just been introduced to a rather subtle effect of cross wind-it produces some vertical deflection.(I don't mean when there are  bumps causing updraughts-I mean pure horizontal wind  causes vertical deflection ...a bit).

   Its a bit complex ( for Jan1st),but essentially follows from the stabilisation of bullets by rifling induced spin. In basic terms,a bullet emerging from the muzzle realigns so that its axis isessentially weathervaning into the airflow it enters. Specifically,here,a crosswind tends to disturb the bullets axis,and when this happens,as  with any spinning object, it gyrates a bit before settling into a new equilibrium (the whole point of bullet spin induction)

   The net relevant effect is a vertical deflection as a result of the pitching and yawing taking place before equilibrium is restored in the crosswind. (The bullet nose wobbles about along a small reducing corkscrew path.) There is a net deflection down for a wind from the left,because of the imbalanced pitch and yaw angles-an example of  aerodynamic jump-though that is more general-eg bullet imbalances etc).Pitch and yaw soon damp down with distance ( similar to what is sometimes refered to as 'going to sleep').RH twist assumed for the description.

 OK ,a left wind deflects a bullet to the right,and down;a right wind left and up

So how much?

Only a 6Degre of Freedom ballistic solver can handle this (the common 3DoF handle only the main three axes-vertical,horizontal and forward (driop,drift,velocity),the 6DoF can add in the  bullet rotations on these axes (pitch,roll,and yaw)...but those also need some pretty fancy input data,generally not to hand...but Litz (who else!) has a formula,though that needs the bullets Gyroscopic Stability factor-available from -yes,him. McCoy "Modern Exterior Ballistics' has one too.What do they tell us:

Mccoy calculates a .35 MOA vertical deflection in a 10 mph crosswind at 100y for the Sierra .30 calibre 168 Match King bullet (Litz equation gives .39 MOA,ver close)

For a Berger 7mm180 VLD from a 1/8 twist barrel,at 2800fps,the Litz quick equation  gives .034 moa  vertical deflection per mph of wind -i.e   .34 moa  (up for right wind,down for left wind),and the more detaled input 6DoF solver gives .36moa,again very close agreement. +/- .34moa isn't  big,but it may well show, (it's well over an inch difference at 200y,if wind is from opposite directions,on two days,eg)

Different bullets (gyro stability factors etc) will give different deflections,but there will be some deflection vertically (and more horizontally,of course,as we all know).

Good shooting.

gbal

ps- your basic 3 Dof  ballistic solver is just as accurate as the  more expensive ones (6DOF etc) given only the same basic 3DoF inputs,so don't rush to upgrade just for the wobble effects ,though it does no harm to be aware of such minor effects.

 

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By all accounts you are fine with StrelokPro upto a 1000m ish the same with most other apps.According to the people who shoot vast distances, the accuracy of the phone apps starts dropping off ,even more so beyond 1500m.I guess it's to only be expected.

The extreme range shooters seem to go for Field firing solutions or Coldbore.

Theres an interesting thread on the hide I inadvertently started discussing which is better called Ffs vs the rest I think

Gluv

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GBAL

I think you are spot on - I got a 0.4MOA vertical deflection - very interesting - not huge but still 1cm at 100m

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On 31/12/2017 at 9:21 PM, Hobbit said:

Hi

I have a quick question on the applied ballistics app

I have inputed all the data as required but am finding an inconsistency between by zero distance (111 yards - short Siberia) and the point at which the output shows zero vertical correction - I am getting the round going through zero at about 65 yards and then back through at 145 yards - I have out the right scope height in 

 

any ideas on where I am going wrong

I think SS is 90 yards not 111 yards. 

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TJC

I was told 100m vs 100 yards and then ranged it with my swaro bins and got 111 yards

I won'y die in a ditch on the subject ;-) but that is the data I have

Cheers and happy new year

 

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On 01/01/2018 at 11:57 AM, Gluv said:

By all accounts you are fine with StrelokPro upto a 1000m ish the same with most other apps.According to the people who shoot vast distances, the accuracy of the phone apps starts dropping off ,even more so beyond 1500m.I guess it's to only be expected.

The extreme range shooters seem to go for Field firing solutions or Coldbore.

Theres an interesting thread on the hide I inadvertently started discussing which is better called Ffs vs the rest I think

Gluv

The thing with all ballistic apps is that the firing solutions are essentially a fudge which use an averaged BC (note that most quoted figures for bullets will be at certain velocities).  Using a G7 once past 300m helps a lot with precision estimation but even then, the actual drag characteristics with velocity vary throughout flight and the only way to truly get a firing soltion to match your load, is to calibrate it to match actual drops. Strelock Pro (and others) have a feature whereby you can enter actual bullet drop with distance V's predicted from initial inputs for MV and BC.  You simply shoot groups at intervals from 100 to 1000m, and compare the drop (measured from POI to group centre in each case) and compare with predictions, entering the data to calibrate your app.  Now the obvious issue here is that you cannot zero for 100m and measure drop from POI at 1000 as targets aren't generally 40ft high!  You can set zero for 100m and measure drop effectively to say 300m, then with sights adjusted to correct the app for 300m to hit POI, shoot to 400m and do the same etc etc.

As Gbal indicates, wind direction and strength have an impact on drop plus you have to be precise about slope angle as distances move further out such that you ensure that true horizontal distances are accounted for, so noting conditions at the time of testing and repeating the tests if not done on a still day are needed if first shot precision matters (as it might for long range "varminting" for example).

Only actual field tests will allow the building of DOPE to become relevant and accurate for each of your loads, not the choice of ballistic apps. Think of them more as a guide to get you on target and NOT as an ultra precision tool. They may get you hitting an 18 inch gong at 1000 yards but to hit anywhere close to centre, you need to work on your DOPE and technique.   No shortcuts to that I'm afraid.  Most people can dial in pretty rapidly for elevation at any distance they shoot to.  Estimating windage and accounting for other atmospheric conditions becomes far more challenging and this is where the black art and skill comes in...that and experience to which there's no shortcut via an App.

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1 hour ago, VarmLR said:

Strelock Pro...

...work on your DOPE...

1. For info it’s Strelok. It’s Russian slang for “gunslinger”.

2. DOPE is what’s known as a “backronym”. The word dope, when used by gun writers back in the Thirties and Forties, was simply US slang for “information” or “data”. Only recently have the US armed forces used it as an acronym for Data On Previous Engagements.

maximus otter

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Yes, it's Strelok.  Never could remember if it was "...ck" or "k".  Yes, I'm aware of the origins of the term "DOPE"..  I don't really care if anyone uses upper or lower case for it, as I know what I mean (Data On Previous Engagements).  Thanks for the corrections though...;)

At least you haven't written "see me" over the front of the post :P

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