Below is a link to a PDF which does give velocities.

According to "Cartridges of the World" the bullet diameter is 0.415" for the old 10.3x60 Swiss which is supposed to be the basis for this new round, which means that the 10.3 in this case relates to bore size rather than groove size. RWS may even be using 0.416" bullet size, hence the reference to a 400 grain bullet (416 Rigby). Interestingly they have included a belt (The gun writers will be having a heart attack), presumably for the same reasons that H&H did it with their early cartridges, namely the small shoulder giving headspace problems. I have no problem with the belt and if the head size is 0.532" then it would be a good all round cartridge which will fit in a standard length action but also be legal for Africa, as well as being good on our Sambar deer.

https://rws-munition.de/fileadmin/rws/bi...A5_12seiten.pdf

Waidmannsheil.