The Nimukei Yosef answers that the shooter is chayav from the moment he released the arrow and set it in flight. It is as if the entire process which will unfold – the arrow’s flight, it’s striking its target, etc. – is all compressed into that instant. So too when a fire is lit, it’s as if the entire process of burning which will ensue takes place at that initial instant of lighting. Therefore, the person is not considered a mechalel Shabbos since the candles were lit before Shabbos started.
Based on this Nimukei Yosef we have a hesber for the machlokes by ner chanukah of whether kavsa zakuk lah or not. The view that holds kavsa ain zakuk lah holds like the maskanah of the Nimukei Yosef – since it is as if everything happened at the moment of lighting, even if the candle goes out afterwards, it doesn’t matter. The view that holds zakuk lah, that you have to relight if the candle goes out, holds like the hava amina, that every second of burning is like a new act, and therefore, you need the process to finish unfolding in order to be yotzei.
The challenge is to shoot the hesber down (he likes knocking down anything I say anyway : )