Ballistic Cal Don’t Match Actually Shots

[N_Turs]

Shooting Rd15 85gr badlands match burners. Don’t know exact mv but am using what others are getting out of the same length proof barrel.

Shot this weekend got a solid 100yard zero.
Used Hornady app to see what drop would be for 300. Move back dial mills all shots high. Shoot some paper and measured with a tape 9.5ish inch of drop. Roughly .7ish mills. I held .6 got hits on 8” steel.

So my question is why is the ballistic app saying I should be seeing 15.7 ish inch of drop but on paper constantly getting 9.5” ish. Even if my mv is off which I’m sure it’s not exact. In the app the bullet would have to be going like 3120 to match what I’m seeing.

Am I just being poor and need to get a garmin and better ballistic app?

 

[oldrifleman]

Shooting Rd15 85gr badlands match burners. Don’t know exact mv but am using what others are getting out of the same length proof barrel.

Shot this weekend got a solid 100yard zero.
Used Hornady app to see what drop would be for 300. Move back dial mills all shots high. Shoot some paper and measured with a tape 9.5ish inch of drop. Roughly .7ish mills. I held .6 got hits on 8” steel.

So my question is why is the ballistic app saying I should be seeing 15.7 ish inch of drop but on paper constantly getting 9.5” ish. Even if my mv is off which I’m sure it’s not exact. In the app the bullet would have to be going like 3120 to match what I’m seeing.

Am I just being poor and need to get a garmin and better ballistic app?

Yes

 

[VargmatII]

In my experience, good data in gets you good data out.
So, you need to match what you got to what the ballistic app is putting out, not the other way around.
This means, velocity, twist rate, scope height and actual BC of the bullet (use the G7 value), that should get you close.

 

[OREGUN]

No. You don’t “need” any additional equipment. You can figure out the speed by verifying the dope at 300 and the Hornady app is as good as a ballistic calculator as is available. But, you do have to be able to use it. Your zero isn’t as good as you think or you have an input screwed up in either the gun profile or the info section of the app, or both. Also, put away the tape measure and stop thinking in inches of drop. There is a ruler in the scope. Shoot at 300 yards, measure distance from point of aim in the reticle, adjust, shoot again. An 8” plate will suck up all kinds of errors. Switch to a 3” square if you want to know how many tenths are actually required at 300. It’s likely just over a mil. Based on what you are reporting, your zero is off or your scope isn’t tracking (if you are dialing) or your holdover marks don’t mean what you think they mean or your distances are wrong. Double check all that.

 

[Ghost29]

Make sure your scope is mounted correctly and its tracking. Confirm the distance of your targets and your 100yd zero. Good fundamentals!!!

Ballistic calculators can get you close but they need to be trued before using them. I use gravity ballistics to dope my rifles, it’s simple to use. Once you have doped your rifle you can true the Hornady app to your rifles dope. You can use the MV and BC off the box then make the following adjustments to true the app.

600 yards & back adjust MV +/- 25 fps .1 mil or 1/4 MOA until the drop lines up (as close as it can).

800-1000 adjust BC second number (.*0*) +/-

 

[Emerson0311]

Garbage in, garbage out. The app is sound. Your inputs, zero, mounting, or optic are not precise.

 

[N_Turs]

I believe I understand my reticle just fine I'm using Burris XTR3 SCR2 .2 mils per hashmark is what I understood. Only reason I used a tape measure was to be able to explain the actual drop I was seeing instead of describing that in mils. I understand how to measure with the reticle and make adjustments. Only thing that makes sense to me is that my ranges were off. But my rangefinder has always been pretty accurate. Ill check all the inputs again. But either way unless my yardages are way off Im still not seeing the drop I should be seeing...

 

[OREGUN]

I believe I understand my reticle just fine I'm using Burris XTR3 SCR2 .2 mils per hashmark is what I understood. Only reason I used a tape measure was to be able to explain the actual drop I was seeing instead of describing that in mils. I understand how to measure with the reticle and make adjustments. Only thing that makes sense to me is that my ranges were off. But my rangefinder has always been pretty accurate. Ill check all the inputs again. But either way unless my yardages are way off Im still not seeing the drop I should be seeing...

Okay so
-reticle means what you think, check.

How’s that zero?
Ranges?
If you dial one mil at 100 yards, does your point of impact move up 3.6”…as exactly as you can shoot?
How about your zero?
What does the ammo box say the speed should be? Is it something wild like 3000 fps? It’s unlikely that reality will be drastically different than the box says.
What’s your group size at 100? Your group size at 300 will be AT LEAST 3x that size. Point being if it’s a 1” gun at 100, your shot dispersion will take you a few tenths in any direction around your POA at any distance.

 

[lash]

Well, u less you start sharing some pertinent information, like caliber, load info, barrel length, what velocity you punched into the app, scope height over bore, etc., you have us all taking pot shots without all the information.

You are essentially asking us, “What is wrong without telling us what you’re doing.” It’s like playing twenty questions.

 

[N_Turs]

I will check and make sure the scope is tracking properly. But I believe its fine in that aspect. Advertised MV is 2900 I understand I'm probably seeing a few hundred feet per second less then that. I do plan on getting a Garmin but will be another month or so before I can snag one. Group size at 100 is about moa and also opened up to about a 3" group at 300 so still holding moa accuracy. I just double check my inputs in the app and unless I'm missing something everything is correct. Which leads me to believe my distances must have been off but I just don't see how unless my rangefinder completely shit the bed...

 

[lash]

And yes, you should buy a Garmin if you plan on doing any serious shooting.

 

[N_Turs]

Well, u less you start sharing some pertinent information, like caliber, load info, barrel length, what velocity you punched into the app, scope height over bore, etc., you have us all taking pot shots without all the information.

You are essentially asking us, “What is wrong without telling us what you’re doing.” It’s like playing twenty questions.

556 85gr badlands match burners, Factory ammo from them. Adveristed MV is 2900, I dont know my exact MV but it should be around 2800 from what others are getting from that ammo. Factory RD15 upper so it has a 16" Proof barrel. Height over bore should be 3.145.

 

[N_Turs]

And yes, you should buy a Garmin if you plan on doing any serious shooting.

I mainly shoot 2 gun stuff but have always enjoyed the long range stuff as well just never have invested into getting everything dialed. For all my precision 22lr stuff I just shot all different distances to get my dope. So using the ballistic calculator is new to me.

 

[OREGUN]

Based on your 85 mb, going 2800, at 4000 ft, 30% humidity, 50* (Arizona?). Here’s what JBM says. Not too far from your 9.5” of drop.

 

[Trigger Monkey]

OREGUN beat me to it, I got similar numbers running it through JBM and Strelok Pro too.

A) Something isn't jiving with the Hornady program.
B) You were a little off on the distance, maybe picking up the background instead of the target.

Those powers combined could throw you off and make you doubt life, the universe, and everything.

 

[lash]

What he said. I got busy so just ran the numbers in another app:

And here’s 2900 fps:

Something is definitely wrong with your inputs into the app.

 

[lash]

I expect that your velocity is incorrect also. Check the results for 2900 above.

 

[N_Turs]

Right on those results are more what I was expecting, something must be off in the app on my end. I was just really confused from what I was seeing on paper from 100 to 300 vs what the app was saying. I'm fairly confident my rangefinder didn't just crap out. I will try and test everything again this weekend and see if I'm getting different results. Sounds like I really just need to get a Garmin and start messing around more.

 

[lash]

Right on those results are more what I was expecting, something must be off in the app on my end. I was just really confused from what I was seeing on paper from 100 to 300 vs what the app was saying. I'm fairly confident my rangefinder didn't just crap out. I will try and test everything again this weekend and see if I'm getting different results. Sounds like I really just need to get a Garmin and start messing around more.

And carefully check that all of your inputs are correct when you built the profile. Every detail needs to be input correctly, ballistics coefficient, G1 or G7 ( it makes a big difference), scope height (from center of scope at front ring to center of barrel/bore), zero atmosphere, etc.

Once you are confident that this is all spot on and your dope is close to matching the predicted drop, you can adjust the velocity to tweak things just right.

Also, when shooting at 300 yards, either use a paper target with an aiming point or paint a waterline on your steel so that you know exactly what elevation is.

 

[Trigger Monkey]

Yeah, check your app inputs. I just downloaded the Hornady app and if I go to the 4DOF calculator, select the match burners, and do nothing else then I get a data output similar to yours, around 16" of drop at 300 yards. Changing nothing else except the velocity to 3120 fps, then the data starts to align with what others posted above from other ballistic calculators. If I change the parameters to what you indicated above and the average atmospheric data for AZ then it aligns more accurately with Strelok Pro, JBM, and lash's numbers.

 

[OREGUN]

Right on those results are more what I was expecting, something must be off in the app on my end. I was just really confused from what I was seeing on paper from 100 to 300 vs what the app was saying. I'm fairly confident my rangefinder didn't just crap out. I will try and test everything again this weekend and see if I'm getting different results. Sounds like I really just need to get a Garmin and start messing around more.

Having a Garmin won’t change a single thing about what happened in this thread. But if you have nothing else to spend your money on, they are nice to have.

 

[N_Turs]

Im starting to think that something was glitching in the app yesterday. I just went back in and punched everything back in and Im now getting the same output as above.

 

[N_Turs]

Having a Garmin won’t change a single thing about what happened in this thread. But if you have nothing else to spend your money on, they are nice to have.

I understand what your saying. I'm convinced something was glitching in the app. Pretty sure my distances have to be within a yard or two. All my other inputs in the app are the same today as yesterday.

 

[LRRPF52]

I will check and make sure the scope is tracking properly. But I believe its fine in that aspect. Advertised MV is 2900 I understand I'm probably seeing a few hundred feet per second less then that. I do plan on getting a Garmin but will be another month or so before I can snag one. Group size at 100 is about moa and also opened up to about a 3" group at 300 so still holding moa accuracy. I just double check my inputs in the app and unless I'm missing something everything is correct. Which leads me to believe my distances must have been off but I just don't see how unless my rangefinder completely shit the bed...

Did you enter your atmospheric data, like temperature and elevation or barometric pressure?

Once you enter temperature and barometric pressure, you can be dead-on with modern programs at 1k.

You need to know your mv though. You also need to know your optic height above bore, measured yourself.

If I don’t measure the critical variables myself, then I don’t trust them.

But mv, baro pressure, and temperature plugged into a modern program (especially doppler) will get you dead-on in my experience.

We’re in a way better place to know where impacts will be at distance nowadays with all the tech we have. I grew up trying to figure out this for myself with practical measurements in incremental distances, then through the theoretical trajectory data era with G1, then G7, then Doppler, Radar chronographs, advanced weather stations, blue tooth, etc.

LR shooting is a lot easier to do nowadays, but you still need a solid foundation in the basics. A lot of tech too soon can really confuse people.

 

[N_Turs]

Did you enter your atmospheric data, like temperature and elevation or barometric pressure?

Once you enter temperature and barometric pressure, you can be dead-on with modern programs at 1k.

You need to know your mv though. You also need to know your optic height above bore, measured yourself.

If I don’t measure the critical variables myself, then I don’t trust them.

But mv, baro pressure, and temperature plugged into a modern program (especially doppler) will get you dead-on in my experience.

We’re in a way better place to know where impacts will be at distance nowadays with all the tech we have. I grew up trying to figure out this for myself with practical measurements in incremental distances, then through the theoretical trajectory data era with G1, then G7, then Doppler, Radar chronographs, advanced weather stations, blue tooth, etc.

LR shooting is a lot easier to do nowadays, but you still need a solid foundation in the basics. A lot of tech too soon can really confuse people.

Yes all the data was entered yesterday when I was out shooting, But again when I reentered the data today its giving me a different output. I'm guessing I may have been in a shitty service area and the app wasn't working properly. I understand to be real accurate I need to know the MV but I was more confused in the difference I was seeing on paper to the app. I will be getting a Garmin eventually.

 

[LRRPF52]

I personally like taking my barometric pressure and temperature in manually with Kestrel, then inputting that data.

Center-punch steel at 1k using that method has been the norm for me for a long, long time now.

You don’t need to shell out $600 for a Garmin either, as there are more affordable chronographs to solve that problem for you.

Garmin is an easy button though, very user-friendly without setting up sky screens or mounting a Magnetospeed.

 

[N_Turs]

I personally like taking my barometric pressure and temperature in manually with Kestrel, then inputting that data.

Center-punch steel at 1k using that method has been the norm for me for a long, long time now.

You don’t need to shell out $600 for a Garmin either, as there are more affordable chronographs to solve that problem for you.

Garmin is an easy button though, very user-friendly without setting up sky screens or mounting a Magnetospeed.

I'm sure I could get a cheaper chrono but the garmin just seems like the way to go. The Kestrel will be next if I keep going on trying to further my long range game.

 

[lash]

Well, April-ish you’ll be able to buy one of the new Athlon Garmin clones for about half the cost of a Garmin.

 

[Trigger Monkey]

I'm kinda glad I didn't get a Garmin to be honest haha...it's like the universe was saying "just wait a minute".

 

[Matches Malone]

I'm sure I could get a cheaper chrono but the garmin just seems like the way to go. The Kestrel will be next if I keep going on trying to further my long range game.

The garmin while a great tool, in this case would just tell you what you already know..your MV is not 3000 fps with 85 gr matchburners.

When you were making hits at 300, was your hits consistent and dead nuts in the center with 8th tenths?

 

[N_Turs]

The garmin while a great tool, in this case would just tell you what you already know..your MV is not 3000 fps with 85 gr matchburners.

When you were making hits at 300, was your hits consistent and dead nuts in the center with 8th tenths?

I was holding between .6 and .8 mils not sure where I was hitting on the plate, unfortunately its a pretty shot up plate in need of paint. Hits were very consistent. Handed the rifle off to my brother he held the same as I was and got hits no problem as well. Its not so much a skill thing, I know I can shoot well enough. Its more of the learning curve I think for using ballistics apps and real data, to be able to shoot accurately first shot.