Who uses G1 or G7 Pros cons

Pappasniper

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Im getting more familiar with my new Ballistic calculator. I started with the Shooters App. and now have the Ballistic AE app. As always they offer the G1 or G7 settings. Which do you use and why?

Pro's Cons if you will.

Any help appreciated.

PB
 

SD carpenter

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Don't quote me... But the g7 is the newer unit of measurement, and also if they kept at g1 the numbers would be pretty high
 

ZY100

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G1 drag model is older and based on a flat based bullet profile. G7 is a newer model and based off a sleeker, boat tailed bullet most of us shoot.

In theory the G7 model is closer to what we use, but the G1 numbers are (usually) based on actual performance (regardless of bullet shape) and end up working well too.

Not smart enough in it to quantify how much “better” one is for our solvers.

FWIW....I use G7. But a lot of people still use G1 with good results. PRS/NRL probably not as critical as ELR....

ZY
 
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ShtrRdy

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The Ballistic Coefficient is made from a "drag curve" which relates bullet drag to velocity. The G1 BC is based on a short-fat bullet with a flat base and broad tip. The G7 BC is based on a slender bullet with boat tail and a pointy tip. To get the closest ballistic trajectory out of a ballistic app/program it's better to use the G7 BC.

You can have some decent results using the G1 BC but the drag curve doesn't match very well over a wide range of velocity. If you've ever looked at Sierra bullet BC being specified for different velocity ranges - this is the reason why.
 

Pappasniper

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Thanks fellas, G7 it is. Im running SMK in 308 and ELD M in 6.5 and 300WM, so yeas G7. Or at least along those lines.

PB
 

Steel head

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G1 works at shorter distances but really falls of the rails at longer distances with bullets common to this activity.
 

Steel head

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G1
BAB66170-B4F3-446D-8A17-A4D9515F0B87.png
G7
F6EB461A-DA74-442B-998E-42E8E2646748.png
Shooting 168’s two weeks to 1200 ago I found the Litz listed G7 to be a lot more realistic to actuals.
 

Jack Master

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The Mathematical Approach
Understanding G1 Vs G7 comes down to fluid dynamics and values used in the equations to define the resistance of flow. Has anyone else recognized the G1 is about 2x G7? Its a mathematical equation (minus Byan Litz' stuff, he actually tests the BCs).
This is a short image of how the BC is derived from a bullet's physical Geometry.

View attachment 7238083
Note the G1 uses the Drag Coefficient of .5 and the G7 used the Stream line Body of almost 0. Once these values are place into the BC equation G1 is 2x G7.

Actual Testing and Truing
Bryan Litz's books push us to use the Measured (not calculated) G7, rather than G1, because the G7 Drag Coefficient better matches the actual bullets we are shooting for long range applications. He also wants shooters to understand the BC of a bullet is changing while in flight. The BC Changes with velocity and where we measure the actual BC of the bullet in it's flight is critical to use in Ballistic Programs. G1 is typically measured at the muzzle or in the first 300 yards of flight where the Velocity is very high. The G7 is typically measured at a further distance, like 600 to 800 yards where the velocity is slowing down. Measuring the BC at a further range for bullets that we are shooting further will give us a better representation of the actual BC average through the long flight of the bullet.

Here are the bullet flights paths that could happen using a bad BC.
G1 BC on very long bullet flight.
View attachment 7238061
Notice the predicted path goes above the actual trajectory and then losses velocity and ends below the actual trajectory. This can make truing our ballistic programs very difficult and pain staking or not possible.

G7 BC on Very Long Bullet Flight
View attachment 7238062
Notice the Predicted Trajectory is much more in tune with the actual Bullet flight. This makes truing our programs mush easier.
Note - If you use a bad G7 BC, you could still get the predicted trajectory of the G1 shown above.

A choice to make
In the end each shooter has to make a choice. G1 or G7. If you are using G1 and getting good results and can true your programs, GREAT! Keep doing that! But, if your program is not giving your good results and its a Bit@h to get it to true up properly switch to the G7 and see if it helps. The HMFIC of this site likes to use G1 rather than G7 because it works for him. Results are what define success. Choose what works for you.

I hope this helps. Happy trails.
 

madpat

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Which one model of bullet is more similar to your? If you use properly u can calculate more precise drag model (drop and wind drift - specific bullet build, resistance etc..)

 

morganlamprecht

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G1
View attachment 7232888
G7
View attachment 7232890
Shooting 168’s two weeks to 1200 ago I found the Litz listed G7 to be a lot more realistic to actuals.
thats because youre using the highest advertised G1 from sierra vs the averaged/calculated G7 from litz

use the velocity banded G1 numbers (or a trued averaged g1) from sierra and the 1200 yd dope is virtually the same
 

sab567

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The Truth is there is not much difference from using G1 or G7 for close or mid range as they both use algorythms to get their curves.
What is saying here is also thrue that using one model or the other depend on your bullet shape (G1 for flat base and G7 for boat tail real bullet).
If only considering that, I'll go with a G7 on a ballistic app to get more accurate performance. It's even more accurate after 1000yrds.

BUT we now have huge improvement in drop chart technology, thank you to Doppler Radar's that give a custom trajectory of a bullet flight over the distance and even at transonic transition and speed. It's why we now have "Custom Drag Curves" that don't need a G1 or G7 ballistic model but can use custom drop based on real test from a Doppler Radar.
It's about the same of a super LabRadar doppler where you can get the speed and drop at different distances and with an algorythm get a custom curves. Witch are even more accurate at long distance.
 

lowlight

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Please explain to me how G7 is "newer" when it was modeled in 1940 and was included in the list prior to WWI

This idea it is new, or better has has been completely debunked

it was ignored for 80+ years until after 2005, the only thing that makes it better is software that weighs it better.

G Dependence is written in,

Nobody here can take advantage of the perceived value of one over the other, which is limited to software used. As noted one can buy excellent ballistic software that you can't even put a G7 value into. When it first started to show up on the market the original ballistic software developers said, Why Bother, it changes nothing the values are, in layman's terms interchangeable.

I can build a track in any program with G1, tune the BC to work, vice versa I can do the same thing with G7, it does not matter in the least. If you match your computer to your actual shots on target, the G value used is irrelevant.

What is really comical most of those G7 numbers are from 300 yards, as if.

These posts with their bullshit answers are pure propaganda
 

jaywhite97

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G1 drag model is older and based on a flat based bullet profile. G7 is a newer model and based off a sleeker, boat tailed bullet most of us shoot.

In theory the G7 model is closer to what we use, but the G1 numbers are (usually) based on actual performance (regardless of bullet shape) and end up working well too.

Not smart enough in it to quantify how much “better” one is for our solvers.

FWIW....I use G7. But a lot of people still use G1 with good results. PRS/NRL probably not as critical as ELR....

ZY

I am on the same boat i use G7 but not as smart
 

lowlight

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There is only two differences between G1 and G7

1. how much muzzle velocity changes the number

2. how your software handles each

otherwise how we use them and the results achieved are identical, especially if you actually true the BC versus just changing the MV

if you true the BC you negate all the bs written here -
There is a reason the original tables focused on muzzle velocity.