Strelok Pro Questions

[bstomper]

I have been playing with my strelok pro app and there are a few things I don't understand. What is the "multiple ballistics coefficent mode" do and how do you use it.
Also when doing my "trajectory validation" which is better to use, the speed or the BC and what would be the difference between using either one.

 

[turbo800]

I believe the "multiple bc" mode is for using banded bc's. Some manufacturers will list a different bc for different set of specific bullet speeds.
I've always heard to start with speed when truing drops.

 

[idcwby]

multiple ballistics coefficent mode - you can set different BCs for different speeds.

trajectory validation - depends on which your more confident in. If you trust that your bullet speed is good, than adjust your BC until it matches your actual trajectory. You can do either, it's just a way to true your trajectory to the program.

 

[bstomper]

Thanks guys
So the multi bc information would be information that would come from the manufacturer of the bullet.... if they have it to provide

 

[idcwby]

Thanks guys
So the multi bc information would be information that would come from the manufacturer of the bullet.... if they have it to provide

Ya, Sierra is good about. There are some others floating around out there. Hornady has a few multiple BCs listed for the ELD bullets.

 

[User4302021]

Basically, at the point where you have lost 25% of your velocity, you drop your BC by 5%.

With most longrange cartridges this will equate to somewhere between 500-600 yards.

 

[swampbug]

IMHO, if you just started using SP, you should not mess with either. It will drive you crazy and probably not be correct.
If you feel like you must, start with velocity in trajectory validation. I use it when shooting past 800 yards to help account for slight changes in velocity due to environmental factors.
But it will change the next time you go out.

 

[bstomper]

I've had strelok pro for about 2 years now so I'm not new at it, I was just curious to those functions as I have never had to use them before and wanted to know what they were and how to use them.

 

[Bang4theBuck]

I have always gotten the best results by using the multiple BC function. It only stands to reason as BC is not a static value. Even if you use some known values for BC degradation with loss of velocity, it is still better than using a static BC.

 

[swampbug]

So yes, some bullet manufacturers publish multiple BC's for some of their bullets. A good example is Hornady for their A Tips. Others use an average. Some of it is even marketing hype. Bryan Litz sells custom drag curves for specific bullets which have actually been doppler verified.
To learn more you should read the articles by Bryan Liz about multiple and trueing BC and velocity. He also has a pretty good podcast about it all. Then you will realize what a dark rabbit hole it is.
Google
The Everday Sniper Podcast: Bryan Litz & Emil Praslick Berger No BS BC Part 1 and Part 2

 

[Bang4theBuck]

One other 'cheat method' ive used (dont judge me) is I've actually picked one of Litzs custom drag models in my kestrel for a friends bullet amd velocity and then modify the BC in whatever solver they are using to get to the same drop/drift as what the custom drag model tells me. Usually helps friends from wasting a bunch of ammo at extreme distances, and gets me off the scope and on the gun sooner too!

 

[lowdowndirtybugger]

I have been playing with my strelok pro app and there are a few things I don't understand. What is the "multiple ballistics coefficent mode" do and how do you use it.
Also when doing my "trajectory validation" which is better to use, the speed or the BC and what would be the difference between using either one.

The problem with bc is that the base CDM is for one specific projectile.
Once anything on that projectile changes so does the CDM.
Multiple bc mode helps correct this. Strelok also has custom CDM mode were you can build your own