We seem to be getting a lot of questions about ballistics on a regular basis on various cartridges. Luckily today we have a lot of tools between Apps and online ballistics calculators that anyone with a decent chronograph can pretty reasonably calculate the flight path of the bullet they are using. However, there is a lot of miss representation of the ballistic coefficient (BC) with bullet manufacturers these days with regards to the G1 BC listed for most bullets.
G1 BC is the most rudimentary of ballistic coefficients, and is actually only accurate for flat base bullet designs. The G1 is also the most misquoted BC used out there, as most bullet manufacturers give a G1 BC to their bullets which results in some pretty amazing BC numbers. However, if you are using a G1 BC with a boat tail bullet you are using the incorrect figure.
G7 BC is the ballistic coefficient for a boat tail bullet with a tangent ogive. If using a ballistics calculator instead of using the manufacturer's BC look for the G7 or Litz BC for your calculations. I'm really only focusing on these two BC types because they cover the majority of bullets being used and discussed in the forums.
Explanation of different Ballistic Coefficients.
Bullet Design-Secant vs. Tangent
Comparing Advertised Ballistic Coefficients with Independent Measurements
For example I shoot a 6X47 Rem (6mm-.222 Remington Magnum) I use a 70 grain Nosler Ballistic Tip with an average speed on 3066 at the muzzle. I don't shoot this rifle at 1000 yards, but it is a good example of the difference between G1 and G7 BC differences as seen in the data below. I think manufacturers like to use a G1 BC because most shooters will never see the differences between the two. I know before I started learning to shoot long range I didn't, but as you can see the BC difference really start to magnify as you approach 1000 yards.
G1
G7
So when you plot your ballistics use G7 (Litz) when you can for boat tail bullets. It will help you to dial in your ranges faster, and maybe save you a few rounds at the rage. Especially when used with a chronograph, it makes your life much simpler.
G1 BC is the most rudimentary of ballistic coefficients, and is actually only accurate for flat base bullet designs. The G1 is also the most misquoted BC used out there, as most bullet manufacturers give a G1 BC to their bullets which results in some pretty amazing BC numbers. However, if you are using a G1 BC with a boat tail bullet you are using the incorrect figure.
G7 BC is the ballistic coefficient for a boat tail bullet with a tangent ogive. If using a ballistics calculator instead of using the manufacturer's BC look for the G7 or Litz BC for your calculations. I'm really only focusing on these two BC types because they cover the majority of bullets being used and discussed in the forums.
Explanation of different Ballistic Coefficients.
Bullet Design-Secant vs. Tangent
Comparing Advertised Ballistic Coefficients with Independent Measurements
For example I shoot a 6X47 Rem (6mm-.222 Remington Magnum) I use a 70 grain Nosler Ballistic Tip with an average speed on 3066 at the muzzle. I don't shoot this rifle at 1000 yards, but it is a good example of the difference between G1 and G7 BC differences as seen in the data below. I think manufacturers like to use a G1 BC because most shooters will never see the differences between the two. I know before I started learning to shoot long range I didn't, but as you can see the BC difference really start to magnify as you approach 1000 yards.
G1
G7
So when you plot your ballistics use G7 (Litz) when you can for boat tail bullets. It will help you to dial in your ranges faster, and maybe save you a few rounds at the rage. Especially when used with a chronograph, it makes your life much simpler.