The actual key to run is shift, but it simply doesnt work as it is suppose to.
There is a strange interaction between shift and LBM about running. When i first start, i thought that LMB(one click) was made to run or walk as it seems wo work well to do so. But i notice a problem with it when you have a gun in hand cuz LMB is the scope key. So i went to change it in config and notice Shift is the actual key to run, but doesnt work as intended. If i 2xShift i can toggle walk or run and even even hold shift to walk. Doing so disable the LMB run or walk toggle ability.