#90

[Rover31]

Ok new topic here, time to move on guys.

What I have been trying to do with the whole bc velocity truing stuff.

I was listening to #90 this am and Frank starts talking about not using a chrono just adjusting MV using drop.
I was like yeah! I’ve been doing that for years! He’s speaking my language!!! Maybe he’ll hit on why it’s not working all the way for me.

Here is my problem... it doesn’t line up well for me at all distances. It never really has.

Unsing AB I go to the velocity truing for a couple of ranges enter the data and it’s all wonky. The velocity goes through the roof and all the data is off...
Why? Lord knows it’s not anything I’m doing wrong! That’s sarcasm folks I’m sure I’ve messed up something... but what? All the data is input but it doesn’t line out.

It’s like a chicken vs egg thing.

Adjust the velocity or the bc first or both or what? Besides the fact I can’t get the Velocity truing to work.

Discussion to follow

 

[Deleted member 113831]

You haven't given enough specifics for an answer. The things that could be wrong are myriad. Read this:

http://appliedballisticsllc.com/Articles/Firing Solution Check List.pdf

 

[Lowlight]

True the BC at 800 and if anything closer is not lining up use MV to make small changes to tweak the close range

 

[Rover31]

Skookum thanks for the reference article.

I will try to be clearer in my ramblings.

I have used AB for quite a while but it never really seems to line up.

When I go to the muzzle velocity truing and input the true drop for 200, 300 and 400yds it changes the velocity from 2875 to around 4200! And then the drops I input are not correct. They are not what I input, why?

I have taken to just using what I actually write down as dope. Very very old school!

I am trying to take advantage of the modem tools we have at our disposal but it’s not working for me.

This is why I reference the podcasts and the bc truing and now the recent one with the mention of truing mv.
So which one is the issue? Which one is first or more important?
Or am I missing something? And, As you say so much to go wrong!

Thanks

 

[Timo Turl]

What are you shooting (caliber and bullet) and what is your actual dope at 200 and 300 to make truing jump to 4200 FPS ? In fact what is your dope out to distance ?

If you are saying that you are truing at 300 or 400 yards then that’s one thing you are doing wrong. If you listen to episode 90 it also talks to a loose rail giving significantly incorrect dope results so make sure your equipment is solid.

 

[Lowlight]

You really can't true inside 800 with AB, it's a two-part process to true, one at supersonic and one at subsonic to line everything up.

But it is easier to skip their methods and just take the real world data, input that, then from your 800-yard drop true the BC, after if anything else needs to be lined up, true the MV to tweak it

The AB method really only works well if you have access to distance, like beyond 1000 yards.

 

[Rover31]

Ok will go for the 800-1000yd drop and see where that puts me.

I can line up the real world drop on paper make a drop chart/range card and it works great. Targets are impacted as long as I follow The Fundamentals.

Looks like Frank answered my base question, true the BC at 800 then tweak the MV.

Thanks