There has been documented tests of railguns launching raw material around those speeds (https://en.wikipedia.org/wiki/Railgun#Tests https://en.wikipedia.org/wik

There has been documented tests of railguns launching raw material around those speeds (https://en.wikipedia.org/wiki/Railgun#Tests https://en.wikipedia.org/wiki/Railgun#Tests). As the sibling comment said, there's no reason to limit ourselves to 3g (yet), and indeed someone laid out a plan to launch material to space with a railgun, where the first "stage" would be a railgun and the second stage would be a traditional rocket (https://en.wikipedia.org/wiki/Railgun#Launch_or_launch_assist_of_spacecraft https://en.wikipedia.org/wiki/Railgun#Launch_or_launch_assis...). It says that acceleration can reach a little less than 2000g. Unfortunately I haven't found any realization of this.