Well, I've been inspired to make a cut-down "prototype" of my .243 Pfleuger cartridge, so I could get a real measurement of case weight, capacity and dimensions.
QuickLoad says I could get 2,902fps with a 100gr Speer BTSP with 30.5gr RL17. The .243Win can get 3,135fps with 48.0gr N560.... So I'm losing 232fps, 7.4% velocity, but using 36.4% less powder.
With a 105gr Berger VLD, I only lose 17 yards on MPBR.
Pictured next to a .243Win
All rights reserved and all that....
Still happily answering to the call-sign Peetza.
The problem, as you so eloquently put it, is choice.
He is no fool who gives what he can not keep to gain what he can not lose.
-Jim Eliott, paraphrasing Philip Henry.