Der pearfect taco...

[Spook]

The third cartridge from the left is 30 caliber and holds just over 13 grains of the little Trail Boss donuts to the bottom of the neck...and, using Benchmark powder,will move a 155 gr Lapua into the high 2600's-low 2700's depending on how long you want your brass to last. Its feeding reliably through two different bolt actions and uses considerably less powder than my .308.
Waiting on the correct barrel extension/bolt to try it out on AR platform but things look very promising on a bolt action build.

[HUNTER2]

Me like!!! The case?

[Spook]

6BR expanded to .308, Shoulder moved forward .100..no turn neck dimension. I cal it 30UAC to keep it unconfused with what could be called a 30 BRX..which has a turned neck.

The interesting aspect should be how consistent sub sonic velocities are by virtue of the "smaller than 308" combustion space .
It should also feed well from AI style and HS Precision magazines.
The difficult part is going to be finding an optimum barrel length that balances subsonic and high velocity performance.
My guess is its going to be somewhere around 18" and a little top end will be lost.
On an AR platform it should be as simple as using two of tp555's adjustable gas blocks and stacking them over two different gas ports.

[Fritzcat]

Very, Very Interesting!

[Rikky Lee]

That is essentially what I have been playing with over the past few years. And it has been hard work!