Re: 6.5 WSM -- 6.5-300WSM ?
With that much case capacity why the 6.5 instead of a 7mm?
The difference in a 6.5-7 WSM and a 6.5-300 WSM is:
7 WSM necked down to 6.5 is going to have less neck length and more powder capacity. 6.5-300 WSM and 6.5-270 WSM are identical to each other, both have a longer neck and shorter base to shouler length than a 6.5-7 WSM.
TO ADD:
Advantages over the 6.5-284 would be increased powder capacity, slightly shorter cases to easier fit in a short action (although a long action would be more optimal for mag length feeding) and about 250-400 fps increase in MV depending on the bullet, barrel lenght, powder, etc.
Downsides:
WSM brass is not available from Lapua, 6.5-284 brass is.
6.5-284's have a short barrel life, expect the WSM to be less than 70% of the already short life.
With a fast twist barrel like a 1:8 you can push the 140's so fast that you're going to risk them blowing up. For a hunting round it's less than optimal if the shot is less than several hundred yards out because the extreme velocities at impact generally tend toward bullet failure.
These are some of the same problems that plagued the 30-378 Wby Mag back in the 60's when it was developed by Weatherby but never released to the market. That, and they had no marketing salient reason to trump their own King of teh 300's (300 Wby Mag)
