A slow day at the day job and some "what if" thought came up with the following:

The 6.5 Grendel, a 6.5 PPC Improved if you will, is about as efficient a cartridge as I have come across and none of my 6.5 designs (on paper) have been able to make significant enough improvement over it to warrant further investigation. So I started looking at the ratios of the various dimensions and what happened if I scaled them up or down.

For starters the 6.5 Grendel. A PPC variant, the case base is 0.445 (or close enough), the length 1.51" and the bullet diameter 0.264".

Scale up/down based on bullet diameter gives the following

0.223 caliber - 0.376 base diameter, 1.275 length. Sounds like the 5.7 Johnson to me, which even in COTW is considered uncanningly efficient for its size. Perhaps using the 22 Rem Jet dies and some Fireball brass you could make a high pressure version. It even heralds to the 224 BOZ which was designed by the same guy who did the Grendel ...

0.308 caliber - 0.519 base, 1.76 length. Sounds like a 1.75" long belted magnum case ... larger diameter than the 300 Savage, but similar length. Might be worth toying with it.

0.338 caliber - 0.569 base, 1.93 length. Sure sounds like the 8.59 Galaxy to me ... or close to it.

0.510 caliber - 0.869 base, 2.92 length. Hmmm, an improved version of the Spotter case would get me there ....

Just thought it was interesting to see what the results were, and that 510 SP(PC)OTTER seems like it might be fun. Shorter than the 50 BMG, wonder if it shoots with any decent results ...

Marty,
Can you make it to the range next saturday?

scaling up the ppc? ... ... ... the BR cases... then a cut down weatherby/jeffery/500jeffery/gibbs?

jeffe