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Trajectory calculator that shows where a bullet first crosses the actual axis of the barrel


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Can anyone help me please.

I have a thermal sight on my rifle and I need to know the range at which the bullet first crosses the axis of the barrel ( possibly around 20m ), and not the second time it crosses the axis of the barrel at 100m which is the range at which it is zeroed.

This thermal sight virtually precludes me from shooting at taget cards to find the answer by convential methods !

 

Can anyone sugest a reloading where it can find / generate this data.

 

Thanks.

 

Tony

 

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You can do the same on Strelok pro, by putting in all your relevant details then go to the table settings and set for 5 yard increments, then just look at the table, this is how i setup my thermal, first zero 85 yards 2nd Zero 235 yards just over and 1 1/4 at it's highest point. this is for a 22.250 using 50 gr Vmax

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  • 3 months later...
On 2/10/2021 at 10:29 PM, tonyshooter said:

Can anyone help me please.

I have a thermal sight on my rifle and I need to know the range at which the bullet first crosses the axis of the barrel ( possibly around 20m ), and not the second time it crosses the axis of the barrel at 100m which is the range at which it is zeroed.

This thermal sight virtually precludes me from shooting at taget cards to find the answer by convential methods !

Can anyone sugest a reloading where it can find / generate this data.

Thanks.

Tony

 

 

Slap me for being pedantic... but... The bullet only 'crosses the axis of the barrel' as it travels along it. After exiting the barrel the bullet will only ever being falling away from that axis on an ever diminishing curve... assuming you hold your rifle the right way up and relatively level(!)

In this instance, the question relates to the curvature of the bullet's trajectory and the single point at which it becomes tangent to the constant of your scope's reticule - if successfully calculated / verified.

It's a good question. There will be a long list of variables to consider though - combining the curvature of your bullet's trajectory whilst factoring in the centreline of your scope from the centreline of the muzzle - especially with a NV/Thermal unit, potentially mounted relatively high. 

As others have mentioned a ballistics app will get you close. Hopefully close enough to then verify with stepped paper targets at 10yrd intervals out in the field before finalising your zero.

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http://www.shooterscalculator.com/point-blank-range.php

Plug in:

Bullet BC

Muzzle velocity

Sight height

Target size (only necessary to get the calculator to work)

The result will give near zero, far zero, minimum PBR, maximum PBR and POI at 100 yards

 

Cheers

 

Bruce

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I use the same setup with Strelok pro on my Android Bruce, takes about 5 minutes to measure and input all the data, providing you don't enter rubbish , you get very accurate data out of it. I'm out on Sunday setting up a keepers NV for MBPR

My own Ward thermal is zeroed at 80 yards with a 2nd zero of 270yards, so point and shoot to 300 which is more than good enough.

 

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Use a hot hands bag as a target for your thermal scope.,

Stick one on a target board at 100 yards (or your preferred zeroing distance) and shoot at the centre of the hot spot

If you can put bullets into the bag you are within one inch of a perfect zero

Remember that you are zeroing a thermal scope, not a target scope, so forget about 1/2" groups, or even 1" groups.  

I also would not be trying to head shoot any animal with a thermal scope - aim for the middle of the heat blob!!

 

Cheers

 

Bruce

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