not sure how easy or if possible it would be to open up the bolt face from .270win to .300win.mag?? or did you mean .300 weatherby?
800yds makes me think of BC's, so perhaps a 7mm STW would make more sense? I do like .30cals though.
I always thought a full length .284 win type case/cartridge would be great for this sorta conversion... ie using the same 270 bolt face diameter but a fatter case of the 284 but rather than a short action it would be a long action.
I found my own answer/kinda! 9.3x66 aka 370 sako, I wonder if this case has been wildcatted to 7mm? if so this would probably do the job I looked it up/compared case volume.... 66.7 vs. 76.0 that's like 15% more volume! with the same bolt face size!
the best conversion might be from .270win to .280 rem AI?? best/possible, at least if using same bolt face dia.
Last edited by salukipv1; 01-26-2012 at 03:54 PM.