FX Hybrid B.C. Conformation

I would have done it today on the range but the wind chill and freezing fog got the best of me and the rifle.

I still need to figure out how to do multiple BC. For instance, if I validate at 100yds, everything out to say 150yds is good but 200yds the POI is low. If I validate at 200yds, it's good at 150 but POI is high inside of 125yds.

I still need to figure out how to do multiple BC. For instance, if I validate at 100yds, everything out to say 150yds is good but 200yds the POI is low. If I validate at 200yds, it's good at 150 but POI is high inside of 125yds.

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Bob maybe the bc profile (g3, g7 etc) is wrong for the projectile and that is why it won’t match up with the charts. 

Perhaps you can play with the software by changing the BC until the computer output matches your observations. That would be a pretty good approximation at least.

There is a multi BC feature.....I just need to figure it out.

Bob_O,

What ballistics calculator are you using? In what device?

Strelok Pro.

I see some guys are using drag profile RA4.....I'll give that a try next time.

I still need to figure out how to do multiple BC. For instance, if I validate at 100yds, everything out to say 150yds is good but 200yds the POI is low. If I validate at 200yds, it's good at 150 but POI is high inside of 125yds.

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Hi Bob. You could try this. 
First use strelok and find your velocity at 100y

Enter this in Strelok as your muzzle velocity (don’t loose you original data!)

Your 50y (zero?)velocity is now actually your 150y velocity. 


Calculate your correction needed in moa to bring your point of impact up to your point of aim at 200y Not the total. Total minus the moa needed for 150y

Now go the strelok trueing app. Enter your range as 100y (actually 200y) and enter in moa the correction you needed and ask for bc not speed. This will give a bc you can enter for the velocity at the 150y mark. 


So in multi bc in the first box put your muzzle velocity and your original bc. 
In the second box put the velocity at 150y and your newly calculated bc. I know that all sounds a bit confusing but it should work

If it’s to cold to shoot you’ll have plenty of time to figure it out!! 
A LabRadar is a great tool to track your velocity but it only works out to 100m so not even that would help you. 
Michael

Bob_O,

I'm using the same Strelok Pro.

It's pretty simple to enter the data for a variable BC.

Just measure your BCs at different ranges, and enter it into Strelok.

Strelok gives you up to 5 BC values for 5 different velocities.



I got the variable BCs for different velocities from the research that Bob Sterne is doing with BCs. Here's the post and his graph — very cool stuff.

https://www.gatewaytoairguns.org/GTA/index.php?topic=14735.msg1265217#msg1265217





Here's the screen shots how to set up variable BCs on my Android:

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[Frankly, I don't know why I keep having problems with posting photos and seeing them here at AGN — other forums don't give me this problem, it's a hit and miss with AGN.... ]







If you want to enter more data, you can enter a custom drag model (CDM). 

Here are the screen shots for that:

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Happy ballisticizing your slugs...!

Matthias