Range Report help me guess my dope

[taliv]

so, i'm shooting berger 140g VLD bullets. litz' G7 BC always worked for me, but i'm pointing them, so it's not quite right anymore. I was using .330 but changed barrels (and thus velocity) and I'm on a new lot of bullets, which you wouldn't think would be a different BC, but apparently is. so i don't actually know what either my velocity or BC is.

anyway, I went out and shot targets today at several ranges and this is what I have so far for data in mils

(temp ~ mid-60s today)
100 yrd zero
400 yrd 1.6 ...couple solid center hits on a plate, but the angle and wind could be fooling me a bit on this one
460 yrd 1.9 ... high confidence
630 yrd 3.1-3.2 ? low-confidence. hits but not sure about range
700 yrd 3.6 ... high confidence
850 yrd 5.3 ... +/- .1

so what combination of velocity and G7 BC matches these numbers? my problem seems to be that i can input numbers that match all of them except one; it puts the 700 yrd at 3.8 or 3.9 and the 700 yrd is the data i'm most confident in.
if i input numbers that put 700 yrd on, it gives me 5.0 for 850, which isn't right either.

wtf?

 

[MitchAlsup]

Re: help me guess my dope

I chose the 0.277 bullet [LITZ] at JBM, Berger has 0.263, 0.277, and 0.288 bulles in VLD format at 140 gr.

3150 fps matches you balistics profile pretty well.

400 yrd 1.5
460 yrd 1.9
630 yrd 3.2
700 yrd 3.8
850 yrd 5.2

 

[timelinex]

Re: help me guess my dope

You mentioned something about angle.. are you account for the fact that if your shooting at an angle, the dope will be different.

 

[Huckleberry75]

Re: help me guess my dope

Since you are guessing your dope, can we assume that you don't have a chrony to verify your data vs. making a scientific wild ass guess?

 

[taliv]

Re: help me guess my dope

mitch, thanks! interesting. the highest single reading i ever got off a chrono with this rifle was around 3080 or so, iirc. and that really beat up my brass so i backed off considerably. i think my velocity is under 3000, but i'd be real surprised if it was over 3020 or so.

timeline, yeah, but it wasn't a very steep angle and my impacts were lower than expected.

huck, you know that saying about a person with two clocks is never sure what time it is? well, when i had one chrono, i believed it. after my 3rd chrono and access to a few others, now i don't believe any of them.

 

[Jedi]

Re: help me guess my dope

Exact BC and FPS ya dont need
Most ballistics program will calc dope based on actual data.
So from a 250 zero, its take 5.75MOA to zero @ 500, plug in what ever BC number is given for bullet
Like magic ... ta da drop table 100-1k
it works confirmed hits out to 1k
So if Exbal can do this sure most other can, hardly guessing

 

[taliv]

Re: help me guess my dope

nm, i got it figured out, thanks

 

[MitchAlsup]

Re: help me guess my dope

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: taliv</div><div class="ubbcode-body">huck, you know that saying about a person with two clocks is never sure what time it is? </div></div>

IN a similar vein:

We don't know the height above bore center on your scope,
We don't know your altitude
We don't know the temperature, humidity, or barometric pressure

All of these interact with the MV inputs to JBM.