6mm Grendel Group Design Project

[LRRPF52]

As a bullet designer that has done a lot of work personally pushing different calibers to their upper limits.
You cannot look at case capacity alone. You also have to look at available pressure.
Available pressure and time under the pressure curve is what makes bullets go faster.
Of course that speaking of internal ballistics and not including rifling profiles, engraving friction and bore lining.

Another thing that is seldom mentioned is the width of the shoulder and how it effects pressure when looking for maximum performance.
This is why Weatherby used the rounded shoulder they did. I am working with a long range bolt rifle company that has went to the Weatherby shoulder in a new cartridge they are designing due to less pressure spiking.
This is also one reason the 30 Herrett can push a 125 grain bullet 2791 FPS from an 18in barrel. Now granted it does not have the high BC you all love, however it does speak to what I am pointing out.

There is a new TAC6 coming out on the 6.8 case.
With the current support by Nosler and Federal on 6.8 case based cats it may be worth looking at.

I do not think pushing the 6mmAR shoulder forward such a small amount will gain what your looking for.

More case capacity with the optimum powder density and burn rate will result in higher mv.

The term you're looking for on the Weatherby design is called a "double radius".

The 6mm AR Turbo is used for this reason over the 6mm AR.

The shorter, fatter powder column in a Grendel or BR-type case will burn more efficiently than an early 1900's type 30 Remington-based case.

It's one of the reasons you see 6.5 Grendel at lower working pressure getting the same speeds as a 6.8 case with the same bullet weight pushed to higher pressures.

It makes no sense at all to use a lower capacity case with inferior shaping to it when we're trying to get more mv, especially with the lower bore volume of a 6mm.