I have been struggling with caliber choice for a build I wanna do and I am curious about one thing. I was leaning towards the 7mm rum because of the high BC of the bullet I preffer the 160gr Accubond. I have a 7stw now and it is all I can do to push that bullet at 3100fps and I have read that the 7rum pushes it around 3250fps. With that I had a real concern about barrel life, so I started looking at the 300rum since it's not quit so over the top. thats when I discovered people were getting 3200fps out of it with a 200 gr bullet which has a higher BC. After running that through my calculator I am finding it superior to the 7mm. How is it poosible to get that velocity out of the same case and a heavier bullet??