Complex sentence: Kolkka is often reported to have killed over 400 Red army soldiers and officers during 105 days of Winter War and as such the second highest scoring sniper of Finnish army in World War II, after Simo Häyhä.
Split into simpler sentences: Kolkka is often reported to have killed over 400 Red army soldiers and officers during 105 days of Winter War. As such he would be the second deadliest sniper of Finnish army in World War II, after Simo Häyhä.