I don't use RL19, but I do use H4350, and I have chrono'd loads using 50gn of that powder behind a 140gn SST getting around 2,800fps. So I'd say you would have to be close to 3,000fps with a 120gn bullet. MY rifle has a 24inch barrel, which is ideal for the 7x57. Not sure about the Rem 700 barrel.
