Not Stopping in Time

There are 3 things I can think of:

• Range, as Wompi already mentioned, could be a factor.
• Perception delay, your perception of opponents firing lags 1 or 2 ticks and then the move starts a tick after that, so maybe 2 or w ticks there.
• Firer inaccuracies. The firer may have a bug (delay as above, firer's movement etc) which causes it for fire slightly differently from what you expect.