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I thought I would ask here.

There maybe a simple explanation but I cannot quite understand this.

I have put my data in Strelok and today zeroed my rifle in on a new load.

I shot out to 100 yards and then out to 180 yards. I adjusted my scope (mil) by .6 mil and was dead centre. I didn't chronograph my ammunition, but based on an assumed speed of 2450' per second the vertical correction is 6.2 clicks which I assume to mean 0.6 Mil.  However I cannot understand why the vertical MRAD correction is 0.4. Am I missing something. Does the MRAD correction not correlate to the vertical click adjustment. Could someone help out and explain why these two  values are not the same.

I have attached a copy of the StrelokScreenshot_20220120-173858_Strelok.thumb.jpg.995d584350ea457c4bd1a280b45ba0e5.jpg

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1/4 MOA (15 seconds of arc) is approximately 0.0727 millradians. As such it would seem your scope may be set up in Strelok for 1/4 MOA clicks?

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Try changing click values to 0.10 instead of the 0.073 . This should make the clicks and mils match up ie 0.8 mils equals 8 clicks if your using 10 clicks per mil .

 Cheers 

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4 minutes ago, levelplaying said:

Thanks Richiew, that's sorted it.

Thank you all for your input and help.

Much appreciated

Glad you’re sorted . Just been checking my StrelokPro and am still learning especially using the wind settings where a bullet spin affect s what a side wind will do to it . Think it’s spin drift ? . A right hand spin bullet will climb up a wind coming from the right and hence need less compensation. Turned these bits on after long range misses at eskdalemuir and found the numbers change quite a bit depending on your wind angle . It’s all good fun when a plan comes together as per the A team lol 

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I use StrelokPro infrequently, but find it very handy. What I also do is keep a Word document that records the challenges that I have found and how they were fixed. I add screenshots to the Word doc. The idea is not make the same mistake twice.

Regards

JCS

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On 1/21/2022 at 11:38 AM, jcampbellsmith said:

Ask Igor to add the reticle to the App for you - igor@borisov.mobi

Regards

JCS

Indeed.

I emailed Igor with a request to add a Hawke reticle to his database. It was added within 72 hrs.

Excellent customer service.

maximus otter

 

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  • 5 months later...
On 1/20/2022 at 9:11 PM, Richiew said:

Glad you’re sorted . Just been checking my StrelokPro and am still learning especially using the wind settings where a bullet spin affect s what a side wind will do to it . Think it’s spin drift ? . A right hand spin bullet will climb up a wind coming from the right and hence need less compensation. Turned these bits on after long range misses at eskdalemuir and found the numbers change quite a bit depending on your wind angle . It’s all good fun when a plan comes together as per the A team lol 

This has caught a few users out!  Spin drift will do exactly that, and is noticeable at longer ranges.  It's due to the Magnusson effect which creates an opposing force proportional to wind strength.  As an aside, some countries experimented with  Magnusson effect "sails" Circa WW1 era whereby cloth sails were replaced by large metal cylinders spinning via motor drive creating the thrust needed to propel the ship.  Exact same forces acting on a spinning bullet, the magnitude of which are related to wind strength and direction.  Litz's ballistic calculator (and others) have a separate column for spin drift.  In order for it to be effective in Strelok,  as well as wind strength, as you've pointed out, wind direction has to be entered and the check box for spin drift enabled.  It becomes essential for first shot target hits much beyond 500 yds but the benefit of including it can be outweighed of course if wind strength is misjudged badly!

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Just now, VarmLR said:

This has caught a few users out!  Spin drift will do exactly that, and is noticeable at longer ranges.  It's due to the Magnusson effect which creates an opposing force proportional to wind strength.  As an aside, some countries experimented with  Magnusson effect "sails" Circa WW1 era whereby cloth sails were replaced by large metal cylinders spinning via motor drive creating the thrust needed to propel the ship.  Exact same forces acting on a spinning bullet, the magnitude of which are related to wind strength and direction.  Litz's ballistic calculator (and others) have a separate column for spin drift.  In order for it to be effective in Strelok,  as well as wind strength, as you've pointed out, wind direction has to be entered and the check box for spin drift enabled.  It becomes essential for first shot target hits much beyond 500 yds on small targets but the benefit of including it can be outweighed of course if wind strength is misjudged badly!

 

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28 minutes ago, VarmLR said:

This has caught a few users out!  Spin drift will do exactly that, and is noticeable at longer ranges.  It's due to the Magnusson effect which creates an opposing force proportional to wind strength.  As an aside, some countries experimented with  Magnusson effect "sails" Circa WW1 era whereby cloth sails were replaced by large metal cylinders spinning via motor drive creating the thrust needed to propel the ship.  Exact same forces acting on a spinning bullet, the magnitude of which are related to wind strength and direction.  Litz's ballistic calculator (and others) have a separate column for spin drift.  In order for it to be effective in Strelok,  as well as wind strength, as you've pointed out, wind direction has to be entered and the check box for spin drift enabled.  It becomes essential for first shot target hits much beyond 500 yds but the benefit of including it can be outweighed of course if wind strength is misjudged badly!

Spin drift or gyroscopic drift is not the same as the Magnus Effect.  Spin drift is due to gyroscopic forces causing the bullet to yaw and therefore create a small horizontal shift of impact. The 'yaw of repose' moves the bullet nose towards the direction of spin, caused by the downward force of gravity, presents a small increase in air resistance moving the bullet towards the direction of spin.

The Magnus effect does disturb the bullet in flight and this in turn can increase yaw therefore affecting spin drift however I've read that the Magnus effect is very small compared to other factors.

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Thinking about gyroscopic force, I guess it has to occur in the direction of barrel twist, so yes, spin drift has to be made up of both Magnusson and gyroscopic forces. I had thought that gyroscopic drift was the tendancy of the tip of the bullet to follow the direction of spin but that this was very small.  I guess over the trajectory distance, it becomes significant

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