The movie script is being tweaked at this very moment. Tom Cruise to play Oscar: even with 'blades' fitted he still comes in at a realistic 6ft or so, therefore saving a fortune in 'real lower leg removal' CGI. Tom is also an aficionado of the movie running scene:
Whether it was his intention to kill his girlfriend over a domestic or to shoot an intruder it was his intention to kill someone. Four shots at a range of 1.5m certainly not a warning shot. And yes he did get around without his legs and went back for them