David:
I will only answer your title question. No - a 25-05 is not a .270.
The old 06 case was, I believe, first made prior to 1906 but the 30 designation was added. Since that time the 30-06 case has been modified by either necking it up or down to different bullet diameters. The smallest that was current was the .22-250. Then the 250-3000 Newton. And the .270. It was necked up to some .35 caliber bullets. I'm sure I failed to list a whole range of others.
Whenever you double the diameter of a circle you don't double it's area - you quadruple it. So going from a .257 caliber ( 25-06 ) to a .277 calber ( .270 ) is actually a bigger step than assumed.
The 26-06 will shoot bullets from 60 grains to 120 grains tops. It is excellent for prairie dogs, varmints and small game such as whitetails, mule deer and antelope. It is not a moose or elk gun although I did shoot a moose with a 25-06. Spined it and it dropped in it's tracks.
The 270 shoots bullets from 90 grains to 160 grains. It is adequate for moose, elk and caribou.
The 25-06 performs better and more accurately on smaller game and varmints while the 270 is better for larger game.
The footpounds of energy are more with bigger bullets.
The rifling twist, bullets size and shape, ratio of diameter to length, BC ( ballistic coeficient ), sectional density all enter into the mix to distinguish the ballistic characteristics.
The two calibers meet and overlap at the high end of the 25-06 and low end of the .270 but they are quite separate at the extremes of bullet weights.
Somewhat similar, yes, - the same, no not at all. The difference, however, is indeed quite small.
Bill Tibbe
