Need help with BC info, and drag models

[hydro556]

Guys, I am using the Shooter ballistic app for my Android device and have a couple questions.

I am trying to determine which drag model is appropriate and the exact BC for the Sierra MK I am loading for my OBR.

Going to chrono it next weekend, but for now I am using the estimated velocity of 2500 FPS from my 16" barrel, because that is the estimate I have heard from other guys shooting this loading in their 16" OBR.(175SMK, 43.5 gr Varget, Lapua brass, Fed 210m, COAL 2.80)

So, should I use the G7 drag model, and what BC would you enter for the SMK 175? Thanks.

 

[Lowlight]

Re: Need help with BC info, and drag models

What a Great Question, and with your OBR, how awesome an OBR, I actually shot an OBR yesterday, how do you like your OBR, I was pretty non-plused about it.

With your OBR, because that is what you are shooting, an OBR, you should use which ever model gets you on target, because your OBR has a 16" barrel, the OBR might only be effective to 800 yards, so really you can just shoot it and write dope down, it's pretty easy to put 2500fps in a computer and get a number that will get you super duper close. Then you have it and don't need anything.

But Clearly the SMK needs the G7 model, which is GREAT, because G7 is shiny and new, and your OBR is shiny and new, so I would stick with Shiny new things, the G1 is dirty and old, and you're OBR is not dirty or old, so avoid the G1 cause after so many years, it's really yesterday's drag model. G7 is where it is at... all the cool kids use G7, cause it's the bomb, just like your OBR.

I have a chronographed MV for the OBR, but guessing is more fun. So stick with that, cause guessing a MV and using G7 is sure to make a difference, guessing and G1 is lame, I don't recommend it.

Good Luck and enjoy your OBR, cause its bad motor scooter, just like you are.

 

[elkhuntinguide]

Re: Need help with BC info, and drag models

Wait a minute... What kind of rifle was that again???

 

[hydro556]

Re: Need help with BC info, and drag models

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">What a Great Question, and with your OBR, how awesome an OBR, I actually shot an OBR yesterday, how do you like your OBR, I was pretty non-plused about it.

With your OBR, because that is what you are shooting, an OBR, you should use which ever model gets you on target, because your OBR has a 16" barrel, the OBR might only be effective to 800 yards, so really you can just shoot it and write dope down, it's pretty easy to put 2500fps in a computer and get a number that will get you super duper close. Then you have it and don't need anything.

But Clearly the SMK needs the G7 model, which is GREAT, because G7 is shiny and new, and your OBR is shiny and new, so I would stick with Shiny new things, the G1 is dirty and old, and you're OBR is not dirty or old, so avoid the G1 cause after so many years, it's really yesterday's drag model. G7 is where it is at... all the cool kids use G7, cause it's the bomb, just like your OBR.

I have a chronographed MV for the OBR, but guessing is more fun. So stick with that, cause guessing a MV and using G7 is sure to make a difference, guessing and G1 is lame, I don't recommend it.

Good Luck and enjoy your OBR, cause its bad motor scooter, just like you are. </div></div>

Dude, I am trying to get specific info for a specific rifle. I figured specifics might be in order.

Thanks for the lack of info.

I shoot every weekend, I am not failing to put in the work. I just want some info I currently do not have. If you think that is being fucking lazy, so be it, you can just withhold the info like you did. I get it, you shoot all day every day, thats awesome and is a blessing I currently dont have.

 

[hydro556]

Re: Need help with BC info, and drag models

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: elkhuntinguide</div><div class="ubbcode-body">Wait a minute... What kind of rifle was that again???

</div></div>

Haha, funny guy. What a coincidence your opinion jives with the site owner.

The bandwagoneering on the internet is fucking hilarious.

 

[hydro556]

Re: Need help with BC info, and drag models

Ballstic apps are new to me.

G1 vs G7 is something I know nothing about. I am currently researching it on the web and get a variety of opinions.

It is a required field in the app I am using, so I am trying to determine if one is better than the other. That simple.

The reason these forums have traffic, which can generate revenue, is because guys come on here and seek info. Which is exactly what I am doing.

Not like I am here asking which scope is best for 100 through 2000 yards.

Its a legitimate question.

 

[Trigger Monkey]

Re: Need help with BC info, and drag models

The G7 for a 175 SMK is .243 I think...that should put your data close to get on target. From there you can adjust the BC to get your ballistic program to match your actual dope. That being said you can also just run the standard G1 BC and still get pretty close to being on target. Before I used the whole G7 thing, I simply used the G1 BC and it worked alright..it got hits on target.

 

[elkhuntinguide]

Re: Need help with BC info, and drag models

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: hydro556</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: elkhuntinguide</div><div class="ubbcode-body">Wait a minute... What kind of rifle was that again???

</div></div>

Haha, funny guy. What a coincidence your opinion jives with the site owner.

The bandwagoneering on the internet is fucking hilarious. </div></div>

I wasn't trying to be funny and I could give a fuck less who owns the site...

A quick search turned up This...

Lighten up Francis... Go out and shoot a little and have fun with the AR10... I mean the OBR...

 

[hydro556]

Re: Need help with BC info, and drag models

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Trigger Monkey</div><div class="ubbcode-body">The G7 for a 175 SMK is .243 I think...that should put your data close to get on target. From there you can adjust the BC to get your ballistic program to match your actual dope. That being said you can also just run the standard G1 BC and still get pretty close to being on target. Before I used the whole G7 thing, I simply used the G1 BC and it worked alright..it got hits on target. </div></div>

Thanks.

What is throwing me, is that I have generated my own data at 300, 575 and 650 yards over the last three weekends.

Then, today when I upgraded to the full version of the app, I was reentering the load info and used the 2500FPS velocity I had heard from other guys running this load in 16" OBR's.

When I input all the info, the data comes back dead on at 300 and 575 yards, matching my real world results. But at 650 I am getting like .4 mils difference.

I am just wondering if my BC data, that I am entering into the app, is the problem.

I am trying to get it as dead on as possible out to the ~700 or so yard max at my main range. So, when I go to private ground and shoot to 1K and a little past, I will be able to trust the app to get me on quickly to minimize wasting ammo.

 

[hydro556]

Re: Need help with BC info, and drag models

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: elkhuntinguide</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: hydro556</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: elkhuntinguide</div><div class="ubbcode-body">Wait a minute... What kind of rifle was that again???

</div></div>

Haha, funny guy. What a coincidence your opinion jives with the site owner.

The bandwagoneering on the internet is fucking hilarious. </div></div>

I wasn't trying to be funny and I could give a fuck less who owns the site...

A quick search turned up This...

Lighten up Francis... Go out and shoot a little and have fun with the AR10... I mean the OBR...




</div></div>
I have been shooting it, constantly. Still have questions, so I am asking them. If you dont have the answers, that is fine. There are folks here that do. And I believe Armalite is the only maker of AR10's.

The rifle I am asking about here is an OBR, made by LaRue tactical.

 

[kyreloader]

Re: Need help with BC info, and drag models

Lowlight and Bryan Litz disagree about G1 vs G7. He may still be upset about this thread.

http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=2407959&page=1

I wanted to give you a little insight into why you got the response that you did from Lowlight.

He is usually a very good resource and has good experience/data. I guess you caught him on a bad day.

 

[elkhuntinguide]

Re: Need help with BC info, and drag models

I am aware of the difference in the 308 Gas gun platforms... I was being sarcastic...

My answers would probably not do you much good as they are tailored for my weapon(s) and it's own ballistics...

 

[hydro556]

Re: Need help with BC info, and drag models

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kyreloader</div><div class="ubbcode-body">Lowlight and Bryan Litz disagree about G1 vs G7. He may still be upset about this thread.

http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=2407959&page=1

I wanted to give you a little insight into why you got the response that you did from Lowlight.

He is usually a very good resource and has good experience/data. I guess you caught him on a bad day. </div></div>

Thanks for the heads up, didnt know about any dispute over G1/G7. But wasnt surprised by the reaction from LL, not a big deal.

Really dont have a dog in that race, I am just trying to get the most accurate estimation I can get from this app, so on the odd times I do get to shoot further than 1K, I can minimize wasted time and ammo by getting on target quickly.

 

[hydro556]

Re: Need help with BC info, and drag models

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: elkhuntinguide</div><div class="ubbcode-body">I am aware of the difference in the 308 Gas gun platforms... I was being sarcastic...

My answers would probably not do you much good as they are tailored for my weapon(s) and it's own ballistics...
</div></div>

I know.

And thanks anyway.

Also, to be clear, I am not asking for any specific info on loads for other guys guns. I am more looking for help with making sure I put the correct info into this "Shooter" app.

This is the first ballistic app I have ever tried, and am not sure why I get perfectly matching data (from the program and my actual shooting results) out to a certain yardage, and then all of a sudden is goes way off. I assume it is something I am inputting incorrectly and the different drag models are throwing me off for sure, because it is new to me.

Just trying to figure out something new.

 

[Lindy]

Re: Need help with BC info, and drag models

Sources of Ballistic Program Inaccuracies

 

[hydro556]

Re: Need help with BC info, and drag models

Thank you Lindy, reading through it now.

 

[Lowlight]

Re: Need help with BC info, and drag models

First off, I have absolutely no problem with Brian Litz or his data, I have a problem with how people use it, case in point this thread.

The Original Poster got the answer he deserved, because if you are too lazy, or not smart enough to understand that "guessing" your Muzzle Velocity isn't going to help you no matter what drag model you use, well he needs to learn a thing or two before moving on. Garbage in, equals Garbage out, and no drag model is going to give you an advantage if you are guessing the variables.

Brian does a lot, his information is certainly well presented, but i live in the real world with a practical mind and I understand people, which the computers used to model don't take into account. People can be stupid, and certain stupid behavior is contagious, which leads to bad information across a larger board -- like the idea you can get accurate data with a "guess" .

See, I have access to an OBR and actually took the time to chronograph the one here, so I have accurate data to use... when you don't have access to things like a chronograph, kestrel, etc, the best thing to do is shoot the rifle at distance and record the results. This is the smart effective thing to do. It gives you the actual data which if you are smart enough, you can do well to reverse engineer the numbers to give you data for a ballistic computers in order to match your "real world data" but you have to have this data first, not second.

His guess is wrong, plain and simply, his thinking is flawed, even easier to figure out... not to mention the reams of data on the 308 which is enough to get anyone on target close enough in order to fine tune your data.

Great, he goes to the range, good, not shoot the OBR and write it down... enough said. Then go buy a chronograph and a kestrel and use it next time. Especially if you want to be specific.

 

[hydro556]

Re: Need help with BC info, and drag models

"See, I have access to an OBR and actually took the time to chronograph the one here, so I have accurate data to use... when you don't have access to things like a chronograph, kestrel, etc, the best thing to do is shoot the rifle at distance and record the results. This is the smart effective thing to do. It gives you the actual data which if you are smart enough, you can do well to reverse engineer the numbers to give you data for a ballistic computers in order to match your "real world data" but you have to have this data first, not second."

If you look at my post #2444111 you will see that this reverse engineering is what led to my question...

By getting that real world data, with my best estimation on the MV (the best I got until I do get to chrono, I have other commitments that dont allow me to shoot daily, unfortunately) the data doesnt match exactly.

I found it odd and wanted to ask some of the knowledgeable and friendly types here that like to discuss such things. So, I did.

And got some help from them.

 

[Guest]

Re: Need help with BC info, and drag models

Myself, I prefer 600 vac secondary's for most all CGW's over 5K #. Add 3/4 oz's of TE/L per gallon, then add 2.4 oz's of det-pro, per gallon and let her eat up the mountains. Det-pro only comes from China now, so order large or struggle like the rest of the pack.

 

[Lowlight]

Re: Need help with BC info, and drag models

Have fun shooting your OBR... and remember, ballistic programs are only a starting point and not the rule of law. Nothing beats recording your data in a logbook and referencing that information when conditions are similar. After all, it is only DOPE, nothing more.

The bullet when shot from any firearm has the last word, every single time.

 

[JLM]

Re: Need help with BC info, and drag models

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: hydro556</div><div class="ubbcode-body">Guys, I am using the Shooter ballistic app for my Android device and have a couple questions.

I am trying to determine which drag model is appropriate and the exact BC for the Sierra MK I am loading for my OBR.

Going to chrono it next weekend, but for now I am using the estimated velocity of 2500 FPS from my 16" barrel, because that is the estimate I have heard from other guys shooting this loading in their 16" OBR.(175SMK, 43.5 gr Varget, Lapua brass, Fed 210m, COAL 2.80)

So, should I use the G7 drag model, and what BC would you enter for the SMK 175? Thanks. </div></div>

I remember you from a couple years ago. At least you are consistent

 

[hydro556]

Re: Need help with BC info, and drag models

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">Have fun shooting your OBR... and remember, ballistic programs are only a starting point and not the rule of law. Nothing beats recording your data in a logbook and referencing that information when conditions are similar. After all, it is only DOPE, nothing more.

The bullet when shot from any firearm has the last word, every single time. </div></div>

We fully agree on that point. That is why I record all my data.

Unfortunately for me, shooting beyond 700 yards is a luxury I dont have very often.

That is why I am interested in having a ballistic app that I can trust to get me pretty close at those ranges beyond what I can accurately document at the range each trip.

 

[BryanLitz]

Re: Need help with BC info, and drag models

G7 BC for the 175 SMK is .243.

As you know, your output can't be any more accurate than your input. The G7 BC input of .243 is solid, so I recommend working on (preferably measuring) the other inputs. Honestly, with so many other uncertainties in your inputs, you could use the G1 BC of .475 and probably not know the difference. In other words, if your objective is to generate an accurate trajectory prediction, I recommend focusing on the bigger uncertainties.

It's my <span style="font-style: italic">hunch</span> that 2500 fps from a 16" barrel might be a bit fast for the factory stuff, but you might be loading hotter?

Good shooting,
-Bryan

BTW (Frank) not everything that's <span style="font-style: italic">new and shiny</span> is a gimmic. Jacketed bullets, smokeless powder, and glass optics were all <span style="font-style: italic">new and shiney</span> once, and those technologies are un-arguable advancements in the state-of-the-art.

Furthermore, not everyone who has an academic background is out of touch with reality.

Because of our very different backgrounds, I think you and I will always butt-heads. However I see that as a healthy balance which usually presents the readers with a bigger picture they wouldn't get fully from either of us.