168 SMK in a .308
Should I be using G1 or G7 drag models on the ballistics AE app?
Thanks in advance.
Waco
Should I be using G1 or G7 drag models on the ballistics AE app?
Thanks in advance.
Waco
G1 or G7?
- Thread starter Waco
- Start date
A G1 drag profile is one based around a bullet like a 9mm FMJ. A G7 drag profile is one based around a bullet like your 168 gn SMK.
See the drag profile shapes about two thirds of the way down the page.
Ballistic coefficient - Wikipedia, the free encyclopedia
See the drag profile shapes about two thirds of the way down the page.
Ballistic coefficient - Wikipedia, the free encyclopedia
They have been using G1 for 70 years without a single issue... it's not cut n dry but a modified curve.
The amount of accurate data with G1 is staggering, you won't find more accurate data anywhere because it has been around so long.
Some ballistic computers favor G7 over G1, while some will not even entertain G7. Using a wiki as a definitive answer is more of an issue than which one. I mean, it's a 168gr SMK, if you can't find solid G1 data you doing something terribly wrong.
Many, many people find G1 to work 100% exactly the same as G7... so saying, "because I read" is meaningless.
Most iPhone apps are written to favor G7 if available, but all of them are weak and just giving you averages anyway. Problem is, G7 is not available for everything, so G1 is easier to get. Again with a 308, you are talking more data than any other bullet on the planet. Either will work exactly the same.
The amount of accurate data with G1 is staggering, you won't find more accurate data anywhere because it has been around so long.
Some ballistic computers favor G7 over G1, while some will not even entertain G7. Using a wiki as a definitive answer is more of an issue than which one. I mean, it's a 168gr SMK, if you can't find solid G1 data you doing something terribly wrong.
Many, many people find G1 to work 100% exactly the same as G7... so saying, "because I read" is meaningless.
Most iPhone apps are written to favor G7 if available, but all of them are weak and just giving you averages anyway. Problem is, G7 is not available for everything, so G1 is easier to get. Again with a 308, you are talking more data than any other bullet on the planet. Either will work exactly the same.
That's indeed comforting, because my loads need to be more accurate. LOL!
Seriously, I have been using G1 for years and haven't been at a disadvantage doing that.
It's two ways of saying the same thing. Are centimeters more accurate than inches? MOA more accurate than Mils?
It isn't about finding out which one to use, the key is in understanding how to use the one you are using.
Just to speak from my own experience, it does really have to do w/ averages. 178g HPBT shows no change until almost 700 yards, then from 700-1000 it's maybe a tenth or 2. So now it's how accurate are you at that distance. For my Berger Hybrids I use the G1 .618 in my Kestrel Horus, but I use my G7 trued dope on my Ballistic AE app. They use different MV to get the same output. So you have to true it up yourself.
Now, not speaking from experience, I've heard that the G7 and Ballistic AE as well as the Applied Ballistics app work better than a G1 profile for ERS with big bullets going transonic. I can't speak to that, but I can understand it. I'll be testing the new AP kestrel soon against my current Horus w/ G1s. I plan on shooting some .308s out to 1500 or so and seeing how the G1 stacks up against the G7 in terms of transonic and subsonic ranges.
Now, not speaking from experience, I've heard that the G7 and Ballistic AE as well as the Applied Ballistics app work better than a G1 profile for ERS with big bullets going transonic. I can't speak to that, but I can understand it. I'll be testing the new AP kestrel soon against my current Horus w/ G1s. I plan on shooting some .308s out to 1500 or so and seeing how the G1 stacks up against the G7 in terms of transonic and subsonic ranges.
Some projectiles have published G1 data at more than 1 velocity point, depending on the ballistic software you may be able to enter multiple G1 points to assist in trueing the calculated results. Single point G1 has worked quite well for me.
