How much are you off? 30fps = 0.1mil at 800 yards, that is a 1% change.It seems odd to me to have to adjust velocity when I got it from shooting through a labradar, is that normal ? I feel like the more likely solution is me entering something incorrectly just not sure what to change
I'm like a broken record saying this stuff, but so many people seem to be right at 1moa off. Which coincidently is about how much change optical effects often have.Thank you for the information, I will collect more data this weekend and report back.
No, continue to use the CDM, and simply adjust MV if its in the Supersonic range or DSF if its in the Subsonic range.Lowlight,
I am using their CDM for my specific bullet the Berger 215 hybrid rather than a G1 or G7 drag should I switch back to be able to fudge the numbers?
I will have to do more testing this weekend but as an example I was on target at 805 using 17.5MOA and the AB app is suggesting 16.75MOA
Doc,No, continue to use the CDM, and simply adjust MV if its in the Supersonic range or DSF if its in the Subsonic range.
the same time software with no real way of actually truing became the preferred method, that whacking the MV outside of the scope of realism was the answer, regardless of the Chronograph model or quality. I have to say when you see the software changing numbers by as much as 100fps+ that is not the chronograph in this case. Plus he is not shooting past 1000 yards.Since when did chronos become infallible?
Say optical effects one more time. I dare you.I'm pretty sure we are in agreement on things. I prefer to use MV at the closer ranges 800 and closer, because chronos aren't perfect and neither are the operators. And...subtle tweaks in velocity have much more effect at closer ranges than BC does. But as you said, within a very narrow range of 1% or less.
Beyond that, if the closer ranges line up, I'm all about some BC change.
Thing is though, once you get out to distance, if you aren't accounting for or controlling for optical effects you just aren't gonna get good data. Light will fuck up a data set in a heartbeat, and it is the least talked about and least understood aspect.
I had a light condition last week that was worth almost 0.5 mils. It was completely canceling a 3mph wind at 902 yards. That kind of difference in the vertical, if you didn't realize it, would do some real damage to any attempt at truing.
If it’s not a real load don’t worry about. Do your load development then true it upI do not have the specific elevation at the target but the range weather station reports 1124 ft, the station pressure I wrote down was from my Kestrel 2500 with reference alt set to 0.
The Averaged G7 BC should provide accurate results in supersonic range. If something in the the rifle has caused a slight variation from the prediction, then tweaking the MV often works for users. The Kestrel used to have SSF, and after much testing and user feedback we found that simply adjusting the MV had the same effect. Simplfying things by removing it, and just using MV Cal. Variation in BC is generally not large before you hit transonic. This is speaking generally, because their are some exceptions. Mostly poor bullet design.Doc,
Why adjust the MV if I know it’s true? If my labradar is telling me what it is for every single shot why would I adjust it? If I’m shooting faster than the velocity you or anyone else used to calculate a BC why wouldn’t I adjust my BC and leave velocity alone?
Asking for f fiend.....
So, is Hornady advocating altering the BC, or the Cd (axial form factor as they call it )?For me,
I look at what Hornady has done, having spent several days in NE with them, and getting a class on their methodology, I want to tune the BC. Here is part of my justification for it, the Curves as outline in the Hornady Data:
Twist Rate Curve Spread
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They have moved to the Axial Form Factor which changes the way we address it, but at the same time they talk BC over MV
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So they go into truing of the BC
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Using just the MV is a working solution but limited in my opinion as these variations will change thus causing issues down the road. MV is not something that stays exactly the same.
A lot of the data used to justify stuff being good enough for what we are doing assumed we all shot relatively short ranges. If you go back and read the original data a lot of these early manuals and ballistic data was for 700 yards and in, most of them are for 400 yards and closer. That is why we SEE the changes now. These changes require we address the issue in a different way.
I think for AB specific issues, the MV stuff works, within reason, but we find to get a better solution, work the BC then make minor tweaks to the MV.
Even David Tubb in my Podcast with him speaks in-depth about working and managing the BC. He talks about a wandering BC valid even if the load has an SD of 0 (zero), that he will see minor fluctuations in the BC value.
We have two choices for sure, MV or BC, I think the more we stretch our legs, the more we'll fine-tune our approaches.