OK if around 88 G of water is the case, I can believe those velocities. I thought case volume was around 100 G, so that is why I was so puzzled. I have a 375 Ruger and it is a good case design and I am sure it works well necked down to .284. What is your shoulder angle on the 7LRM?
I built a 30-338 Lapua Imp. last year which would push a 210 Berger over 3,400. My finale load was 105 grains of Retumbo at 3,225. Fortunately someone wanted it more than I did so I sold it and built the 7 Dakota
Imp.. Sure the Lapua case is a beast but the 7 Dakota will do anything it would do and passes it at 1,000 yds. The 7 Dakota Imp. is much more pleasant to shoot and also more accurate than the Lapua. So I feel the same way you do about choosing over the high performance 30 calibers.