Nothing so far addresses the fact that a 270 a 270 WSM seat the bullet deep into the powder column. The 6.8 Western along with the appropriate barrel throat keeps the bullet base at the neck of case so there is more space for powder and less turbulence when things are burning.
While this has been written by a few "gun writers" because, apparently, it is in the press release they used to write their articles,
do the math and you'll see it's not true. In fact it's blatant nonsense.
The 270 WSM and the 6.8 Western cases are identical except that the WSM's shoulder is .08" further forward. almost a tenth of an inch MORE powder capacity in the case. It and the 6.8 Western typically come in a rifle with a 3" (or a hair more) magazine box. So both will be loaded to the same OAL by the handloader. The .270 WSM has more powder capacity.
And take a look at the length of the bullets that go in the 6.8 Western. Even if loaded to absolute SAAMI max OAL, the base of the Sierra 175 TGK (1.641" long) sits over one tenth of an inch
below the base of the 6.8 Western's neck. At SAMMI min OAL, it's 0.3" below the base of the neck. At the same OAL, the 270 WSM with have the same bullet seated .08" further below the base of the neck, but that bullet shank will be surrounded by powder that the 6.8 Western, being a shorter case, just can't hold. Load to the same pressure, the .270 WSM goes faster.
No offense - it's just math.
Cheers,
Rex
