New Page 2

Donate to TalkHunting

 

 

 

!!

You are a Guest at TalkHunting

As a guest here, you are able to view some of the topics to get a feel for how this site works. However, you will not be able to post replies until you become a member. We hope that you will register (free) and become a member. This will open up all of the website for you to see. We are a very friendly group and we do not allow any bashing, fighting, or vulgarity. If you are looking for a family friendly site to talk about hunting, you have found it here at TalkHunting. You will find this a very comfortable and friendly place to visit and hang out. We hope to see you soon!

If you are having problems getting registered or you didn't receive your activation email, click the "Contact Us" link at the top left of this page.

New Page 3

Google Ad

Google Ad

Author Topic: G1 and G7 What is the Difference and which one should we be using?  (Read 237 times)

Offline BoBallistic

  • 14 Point
  • Join Date: Oct 2009
  • Posts: 5634
  • Location: Tennessee
  • Share Your Knowledge
This is from Kestral Website and just curious about the subject, so I thought I would not try to explain it my way and thought that others should give it a go....this is the last weekend in June 2020 and it is time to start going to the range, and some of you would have questions about the difference between the G1 and G7 BC....it is a long calculations that I have somewhere in a Excel spreadsheet....

G1 & G7 Ballistic Coefficients... What's the Difference?

Ballistic Coefficients are measures of objects’ abilities to overcome air resistance mid-flight.  Typically, the higher the number, the lower the drag of the projectile (low negative acceleration), and the better the bullet will cut through the air.

For the more technically minded, ballistic coefficients are derived from the mass of the object divided by its diameter in the airflow squared, divided by the form factor, i, that relates to the aerodynamics of its shape.

The formula is seen below:

An issue with accurately measuring flight characteristics of a bullet is that any mathematical model must differentiate between the many types of bullets and shapes; bullets of different shapes yield different drag curves, and cannot be modeled by a single formula.  Because of this, several different drag curve models have been standardized for common projectile types, and are shown below:

G1 – also known as Ingalls, G1 projectiles are flatbase bullets with 2 caliber nose ogive and are the most common type of bullet.

G2 – bullets in the G2 range are Aberdeen J projectiles

G5 – G5 bullets are short 7.5 degree boat-tails, with 6.19 caliber long tangent ogive

G6 – G6 are flatbase bullets with a 6 cailber secant ogive

G7 – Bullets with the G7 BC are long 7.5 degree boat-tails, with 10 caliber tangent ogive, and are very popular with manufacturers for extremely low-drag bullets.

G8 – G8s are flatbase with a 10 caliber secant ogive

GL – GL projectiles are blunt lead nose
NRA Life-Endowment-Patron Member
RMEF Life Member
Buckmasters Life Member
2019 NWTF Member
Proud Member of Butts County Sportsman Asso
20 yrs of Western Elk/Muley/Antelope Hunts
2009 & 2011 African Safaris
Share Your Knowledge

TalkHunting Community

New Page 3

Google Ad

Google Ad

Offline Madgomer

  • 2016 TH Turkey Champion
  • 14 Point
  • Join Date: Oct 2013
  • Posts: 5281
  • Location: Central IL
Re: G1 and G7 What is the Difference and which one should we be using?
« Reply #1 on: June 26, 2020, 09:30:30 AM »
The ballistic calculator I use most often is Hornady's online version.  I generally just stick with the G1 calculation, but I'm also typically only looking at 0-250 yard output data.  None of the models can be expected to correctly account for all of your specific variables, so rather than expecting an absolutely precise prediction, you really need to use them to look at the magnitude of change from one configuration to another.  There are a lot of different sites to choose from for these calculators, what's your favorite?
One of God's greatest gifts to us is
the great outdoors - get out there
and enjoy it!

Offline BoBallistic

  • 14 Point
  • Join Date: Oct 2009
  • Posts: 5634
  • Location: Tennessee
  • Share Your Knowledge
Re: G1 and G7 What is the Difference and which one should we be using?
« Reply #2 on: June 26, 2020, 04:08:45 PM »
Mad - Same goes for here. I too have always used the G1......for all these years I too have been using the G1 Ballistic Coefficients when I do my chart loading by pumping in the G1 BC into my QuickLoads and my Oehler (those are the two that I currently own).....

But looking at the G7 bullets shapes and the long range bullets profiles, one wonder when and why folk will use the G7 B.C....I'm they type guy who hunts with what he shoots at the range...Are most of the Ballistic Tips and Accubonds G7 ?? and how bout those Berger's and Barnes TTSX or those Sierra GameKing and those Game Changers should you be looking at the G7 becuase of their shapes ??

But like you Mad, I have always been looking at the G1 for the BC....and Lordy, my range is at most 125 to 150 yards.....was just wondering.....Bo
« Last Edit: June 26, 2020, 05:26:40 PM by BoBallistic »
NRA Life-Endowment-Patron Member
RMEF Life Member
Buckmasters Life Member
2019 NWTF Member
Proud Member of Butts County Sportsman Asso
20 yrs of Western Elk/Muley/Antelope Hunts
2009 & 2011 African Safaris
Share Your Knowledge

Offline notsams

  • Mar/11 Prize Winner
  • 7 Point
  • Join Date: Dec 2010
  • Posts: 746
  • Location: minnesota
Re: G1 and G7 What is the Difference and which one should we be using?
« Reply #3 on: June 28, 2020, 04:48:35 PM »
     I use the G7 BC because the bullets I am shooting are close to a target bullet shape or they are target bullets. Using these ballistic programs will help you get on target at long range, but not perfect. Bullet companys inflate the BC of there bullets to help sell them. Very few are exact. I had a turret made for a friends 300 RUM and it goes to 750 yards. What I will do is zero it at 500 yards exactly. The turret is set to zero at 250 yards but if we zero it exact at 500 yards and it is 1 inch high or low at 250 yards it doesn't matter. If it is exact at 500 yards it will be closer to being exact at 600 or 700 yards too.  Out to 600 yards the elevation and temp or humidity will have very little effect an the 300 RUM bullet. On my 6mm Creedmoor the turrets zero is 200 yards but I zeroed it at 700 yards and that way I have a better chance to be exact at 1000 yards. But at 1000 yards all the little things are really starting to effect point of impact.    I live at 1074 feet elevation. When I go to Colorado at 10,000 feet Elevation my 7mm Mag shoots about 9 inches high at 800 yards just because the air is thinner and has less effect on the bullet.              This seems to work for me but you have to know when the little things start to effect your bullets.   JMO

Offline BoBallistic

  • 14 Point
  • Join Date: Oct 2009
  • Posts: 5634
  • Location: Tennessee
  • Share Your Knowledge
Re: G1 and G7 What is the Difference and which one should we be using?
« Reply #4 on: June 29, 2020, 05:39:35 PM »
Not - I see you point...I would use the G7 BC if I shot a 600 to 750 shots. I too love Berger, Barnes and Sierra and Nosler LR bullets.....

I use those LR bullets when I reload my favorite 308 loads, I use mostly the Berger 155 Gn bullets along with Viht 140 Powder...having said all that I was reloading some Sierra Pro Hunter bullets for one of my 308's today....loaded up 24 bullets using the Viht 43.28 gn and having a OAL of 2.816" it was for an F&N 308". I had used those bullets with great success in "Stumpy" because it has a 16" barrel...shots 6, 7 & 8 went though the same hole at 100 yards....

What bullet was I using is a Sierra Prohunter #2130 in it...you certainly would call this a G1 BC...LOL...it is a Spitzer design with a flat base!! I have always read where a flat base bullet would keep up with a boat tail design to about 300 yards, the because or its aerodynamic shape it takes over and travels farther....

So after reloading the 24 bullets I had left I ordered another 400 rounds of Sierra 2130 flat base Spitzer bullets....LOL....
NRA Life-Endowment-Patron Member
RMEF Life Member
Buckmasters Life Member
2019 NWTF Member
Proud Member of Butts County Sportsman Asso
20 yrs of Western Elk/Muley/Antelope Hunts
2009 & 2011 African Safaris
Share Your Knowledge

 

New Page 3

Google Ad

 

Google Ad

Google Ad