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.