msquared,
Several things:
The 6mm Remington's powder capacity is very close to the .243 Winchester's. When handloading you can make either one do basically the same things.
Many hunters still judge cartridges (or handloads) by muzzle velocity, which is natural since higher velocity was the best way to flatten trajectory since smokeless powder was introduced. But that changed in the past couple decades, as more high-BC bullets were introduced. What really matters is retained velocity, and while a short-barreled 6mm Remington may get 100 fps less with the same load using, say, Nosler Ballistic Tips or Hornady SSTs, the retained velocity is a lot better than it was when both rounds were introduced.
In a typical 2.85" magazine, even higher-BC bullets might not be practical--but if you only shoot deer at "normal" ranges (300-400 yards) so what? The difference in trajectory isn't enough to notice.
Thanks for the input, I'm probably overthinking it. I would have expected more velocity loss in a Model 7 (I didn't say so but, I was mentally comparing it to a 24" barrel). But, even so, as you suggest the loss is nearly irrelevant.
I will admit to having an emotional attachment to the 6mm Rem. as it was my late brother's favorite cartridge. It's also time for me to switch to a lighter recoiling rifle. So, the 6mm is tempting and has a strong pull on me. But, is the .257 Roberts a better idea? It seems to do everything the 6mm does with similar recoil, while leaving the door open to heavier bullets for game larger than deer.
