There are many new powders and chambers that can make most things possible, But at what cost.
Time and time again I see where someone wants to push there favorite cartridge faster and faster.
This all comes with a price and is not free. there are some easy ways to gain velocity without increasing pressure. Then there is the increasing of the pressure to gain velocity.
There is no magic formula for increasing velocity in a standard cartridge. Pressure = velocity and efficiency can improve velocity but only so much. barrel length also has a bearing on how much velocity can be achieved at the same pressure.
Having worked on many rifles that were over pressured, the effects are easy to spot and very costly for the slight increase in velocity. (Nothing is free). at One time I had the velocity bug for 1000 yard matches and paid dearly for it in damaged equipment and components. I finally saw the error of my ways and stopped tearing everything up.
Knowing how to increase velocity without more pressure is valuable but it requires a commitment that Many are not willing to make, Because adding powder does it instantly and is easy.
We are talking about the 308 on this post and it is a good example to discuss. First, target a pressure. 62,000 Psi is SAMMI max. Many things determine why SAMMI sets this pressure and recommends that you don't exceed it. Of coarse you can, but at what cost. Next, Target a velocity for what you need within the pressure limits by trying different powder burn rates for the barrel length you have. If this is practiced, you will get great accuracy and life of your equipment and components.
If you want/desire more that this will get you, then you have to make some decisions. The easiest
way is to AI it. This will add case capacity and efficiency without increasing pressure and changing the action. Adding a little free bore will also increase the velocity and hold the pressure to the SAMMI limits. If you still want more, then it is time to change to a bigger cartridge like a 300 WM.
The 308 Is a very good cartridge in it's original form and at or below it's design pressure, so don't expect more of it than it was designed for or the problems will only increase as the pressure does. My match rifle has over 23,000 rounds through it and with iron sites will still shoot 1/2 MOA.
Just My Opinion and recommendation.
J E CUSTOM