Truing BC in BallisticsARC

[pewpewfever]

I’ve been reading about truing velocity vs BC, and it looks like at least some people true for velocity at closer range (eg 500 yards) and true for BC at longer range (eg 800 or 1000 yards). I’m thinking of trying this method, and I see how to true for velocity in BallisticsARC using the tool where you just tell it the difference in mils. But I don’t see such a tool for truing BC. Am I missing it, or does everyone just enter custom bullet data to true BC manually? To adjust manually, is there math for figuring out the BC or the difference in BC from the number of Mils, or is it a trial and error data entry to look for a match? If trial and error, do you raise the BC for high point of impact and lower it for low POI? Does a kestrel have more truing options?

 

[beenjammin]

Dont hold me to this, but it seem like I remember being told to true at two nodes ( super sonic and transonic?) 600 and 800-900 for the .308.

What I ended up doing was adjusting my kestrel off a good group I shot at 900 by changing the velocity of the round a few fps until the kestrel matched. i think checked the ranges back down to 600 and it was all within 0.05-0.1 mil which seemed good to me. Prob not the right way, but works

 

[Lowlight]

Ballistic Arc should let you band the BC so you are not using a single average number

I just started using it with a beta program they are doing and the initial load in the program was banded

Much better to add the banded numbers vs a 1 number average

 

[pewpewfever]

Ballistic Arc should let you band the BC so you are not using a single average number

I just started using it with a beta program they are doing and the initial load in the program was banded

Much better to add the banded numbers vs a 1 number average

Thanks. I see that in the factory ammo option, there are three BCs banded by velocity for the 6mm creedmoor 108gr Hornady ELD Match ammo, and they don’t seem to be editable. But if I select to manually input bullet info, it only lets me provide 1 BC. As long as I am using that factory ammo, is it better to stick with the preset banded BC and just true mv?

 

[Lowlight]

I have to dig deeper but I bet even manually they will let you use it,

I can email Joe and see if I can get a answer

Truing the BC definitely helps over time, distance and range. But banding should be even better because it's how the bullet flies and BCs are moved by velocity.

 

[pewpewfever]

Perhaps I should clarify that I’m using the BallisticsARC app for iPhone. Thanks again.

 

[GeoJoe]

Thanks Lowlight. Noted observations are correct. There is not a UI for entering multiple BCs in BallisticsARC. At the moment, I can add banded BCs, or scaled as we call them, on my end and push them out in the library for immediate use. We have user entry wireframed, but for lack of excuses we haven't added that feature yet. We'll revisit this and see if I can attach some goals for this feature release. In the meantime, if I can add any profiles for anyone, please let me know. The best method of contact is [email protected]

 

[2aBaC̶a̶]

Noob question.
Why are there 4 different profiles for the same bullet " 6.5Cm Hornady 140gr ELD Match" and how would I decide which one to use?
-Regular
-G7
-G7 scaled
-mach 1.75

 

[GeoJoe]

Good question. Hornady released the data before we offered support for banded BC entry on our end. I could’ve deleted the piece milled profiles, but I left them in the event users had already attached those to a rifle profile. For the last year, I’ve only added the scaled G7 as they’ve made the data available.

 

[2aBaC̶a̶]

So just starting out today is there a reason I would choose one over the other or would you recommend go G7 scaled.

 

[GeoJoe]

So just starting out today is there a reason I would choose one over the other or would you recommend go G7 scaled.

So just starting out today is there a reason I would choose one over the other or would you recommend go G7 scaled.

G7 scaled. For sure.

 

[pewpewfever]

In order to develop my own banded BC, would I create multiple rifle profiles, one for each band, use one BC for that band specific rifle profile, and just tweak them until they each produce solid predictions within their specific bands?

 

[GeoJoe]

In order to develop my own banded BC, would I create multiple rifle profiles, one for each band, use one BC for that band specific rifle profile, and just tweak them until they each produce solid predictions within their specific bands?

No, you won’t be able to negate a previous band by only inputting one BC. Let me spend some more time on this. I’d rather spend the time building the interface for you to do it yourself rather than building workaround but I’ll see what I come up with. It’s evident we need to move forward on this feature. Like I mentioned before we have a really nice advanced modeling interface wireframed. It got shelfed as other immediate items took precedence. Let me get back to you. Thanks for using our system btw. It’s humbling to watch it evolve get utilized by so many serious shooters.

 

[seansmd]

I have to dig deeper but I bet even manually they will let you use it,

I can email Joe and see if I can get a answer

Truing the BC definitely helps over time, distance and range. But banding should be even better because it's how the bullet flies and BCs are moved by velocity.

I tried as well not editable, 140 eldm pastes them in and my dope lines up with AB with the custom curve. If you load the normal 140 eldm it would let me add multiple BC and bands.

 

[Diver160651]

I have to dig deeper but I bet even manually they will let you use it,

I can email Joe and see if I can get a answer

Truing the BC definitely helps over time, distance and range. But banding should be even better because it's how the bullet flies and BCs are moved by velocity.

On a side note, the very coolest thing about BA is its robust range cards.. almost like FFS in that you can have as many targets with individual AOF, DOF and of course range with seemingly as many range cards as you might need, then flipping back and forth between loads or systems updates as it should..

Even prints out nice for stages

 

[fxdrider]

Just bought the full version of the app yesterday and am really impressed with the features offered. Can't wait to try it out at the range. I do have a question though. In some ballistic apps, (Ballistic AE, Trasol, for example) when inputting info for your rifle there's a place to enter weather/atmospherics data for the time the rifle was zeroed. That data is then saved with the rifle's profile and compared against current atmospherics when determining the current firing solution.
I don't see that feature when adding or editing a rifle in BallisticARC. Am I missing something?
Thanks.

 

[Diver160651]

Just bought the full version of the app yesterday and am really impressed with the features offered. Can't wait to try it out at the range. I do have a question though. In some ballistic apps, (Ballistic AE, Trasol, for example) when inputting info for your rifle there's a place to enter weather/atmospherics data for the time the rifle was zeroed. That data is then saved with the rifle's profile and compared against current atmospherics when determining the current firing solution.
I don't see that feature when adding or editing a rifle in BallisticARC. Am I missing something?
Thanks.

That is a legacy feature when guys used t o think a long range zero like 300 &600 yard zeros were important.

A SOLID 100 yard zero; a small group - measured either with the offset or dead center is more valuable than any atmospheric conditions at 100 yards.

Zero at 100 and forget it. I’ve seen people have lots of trouble zeroing using atmospheric conditions then working with the program in an analytic way and get themselves screwed with the zero atmosphere switch.

edited to add: I was not thinking of anyone particular, but some of the early CB and FFS users that got spun around.

 

[fxdrider]

That is a legacy feature when guys used t o think a long range zero like 300 &600 yard zeros were important.

A SOLID 100 yard zero; a small group - measured either with the offset or dead center is more valuable than any atmospheric conditions at 100 yards.

Zero at 100 and forget it. I’ve seen people have lots of trouble zeroing using atmospheric conditions then working with the program in an analytic way and get themselves screwed with the zero atmosphere switch.

Interesting. That would explain why some apps don't have that feature.
So, if I'm understanding correctly - I shouldn't bother recording weather data when zeroing. I'm assuming that would also apply to load development?

 

[Diver160651]

Interesting. That would explain why some apps don't have that feature.
So, if I'm understanding correctly - I shouldn't bother recording weather data when zeroing. I'm assuming that would also apply to load development?

Load development @ 100, I would record the temp.. but that's more to see if your getting pressure or velocity shifts related to temp.

But not solely for 100y/m zeros.

 

[GeoJoe]

Interesting. That would explain why some apps don't have that feature.
So, if I'm understanding correctly - I shouldn't bother recording weather data when zeroing. I'm assuming that would also apply to load development?

So, mathematically a 100 yard zero for most rifles (nominal center fire velocities and scope heights) will have virtually immeasurable vertical POI shift in DA swings of even 10,000 ft. As you extend the zero range, this will obviously play a larger role. This is one example of a feature we just left out in the name of design and keeping things simple. Maybe look at keeping a round count book and recording ambient temp, ammo storage, and avg MV.

Our next version of BallisticsARC has a notes section attached to each rifle profile that would be a great place to keep this info.

It is my opinion that real world POI shift in an extreme environment is most likely attributed to powder temp. I realize that several apps offer a tool for tracking MV vs temp, and we still don't. This is another example of filtering noise in our solver. I'm just not a fan of making a direct correlation of ambient temp to MV. There's at least a couple more steps in that process. It will work in cases, but it's not 100%. I would rather force a user to track this type of info in a log book and identify MV stability (with not only ambient temp, but also their ammo storage and carry habits) than offer a crutch that only works half the time.

 

[Crews]

It is my opinion that real world POI shift in an extreme environment is most likely attributed to powder temp. I realize that several apps offer a tool for tracking MV vs temp, and we still don't. This is another example of filtering noise in our solver. I'm just not a fan of making a direct correlation of ambient temp to MV. There's at least a couple more steps in that process. It will work in cases, but it's not 100%. I would rather force a user to track this type of info in a log book and identify MV stability (with not only ambient temp, but also their ammo storage and carry habits) than offer a crutch that only works half the time.

This is a very interesting subject to me, and something I have been wondering about for a while. I live in Houston, so it is almost NEVER cold. I really don't see a lot of variance in MV based on ambient temperature. However, I hunt up on the Red River (much further North) where it will actually get cold sometimes. So all of my data is based on gulf coast weather, but that one cold bore shot on a below freezing December morning has got me worried. This probably warrants a different thread, because I bet it's a deep dive. But I'd really love to hear some more detailed discussion on this topic.

 

[pewpewfever]

This is a very interesting subject to me, and something I have been wondering about for a while. I live in Houston, so it is almost NEVER cold. I really don't see a lot of variance in MV based on ambient temperature. However, I hunt up on the Red River (much further North) where it will actually get cold sometimes. So all of my data is based on gulf coast weather, but that one cold bore shot on a below freezing December morning has got me worried. This probably warrants a different thread, because I bet it's a deep dive. But I'd really love to hear some more detailed discussion on this topic.

I don’t know for sure, but I think one way to check effects of powder temperature is to take your cooler to the range and keep your rounds on ice. But you also have to take into account the amount of time the round is loaded into a hot, freshly fired barrel before pulling the trigger. I’ve seen a benchrest shooter keep his rounds on ice and wait 15 minutes between each shot at the range. Maybe try something like that?

 

[GeoJoe]

I wouldn't get too caught up in this. A 100 fps drop will create a mathematical POI shift of about .25in at 100yds (175 SMK from 2700-2600). Most powders used by long range shooters have at least that much stability in their normal operating temps. It is the biggest measurable shift for the things we measure though. (edited for redundancy.) "It is a more measurable shift compared to tracking DA at the time of zero.)
I also subscribe to the theory of cold shooter shift vs cold bore shift. Rifles Only is a proponent of dry firing to help eliminate poor fundamentals on that first shot.