Lets start over: how do you design a GPC?

[mongoosesnipe]

That last image is simply there to illustrate what extrapolating the 5.45 7N6 form factor would look like when placed in existing cases. It demonstrates the importance of case length and diameter and how they affect COAL, which will determine action length of the weapon and magazine size. Every single one of those examples exceeds the current magazine dimensions for any of the intermediate cartridges, with the possible exception of the new Chicom 5.8x42mm.

I know I was just poking fun since the listed specs were pretty much fit by an existing cartridge wich was made with a shorter case to accommodate longer bullet. That bing the 6.5x47 which if you want to get down to it isn't a shortened 308 but a reformed 250 savaged which spawned the 300 savage which was the parent case for the 308 but they wanted a little more power so they added 4mm worth of powder to the case and raised the pressure spec...

The military isn't actively hunting for new cartridges and platforms but there are small number of what I lie I call door kickers that do often try and field new equipment that isn't field by the rest of the military