RWS case capacity

[Stats Shooter]

I'm looking at getting some RWS brass for my .300 wm, but the case capacity concerns me a little. I have never used this brand in any cartridge. I have heard it is Lapua quality, and lake city toughness.
But if the internal volume is less is significantly lower than Remington, Which in this cartridge is about 5 gr of water weight less than Winchester, then I won't bother.

Simply because I don't want to turn a .300wm into a .300wsm performancewise, and this is intended for hunting so I won't be loading it that often such that I can just get Norma or something even though it won't last as long.

Thanks