Insignificance" or "significance"? If lock time were insignificant, why does it take "highly skilled" shooters to shoot a Sharps at 600? Isn't it likely these shooters would tell us that it is these conditions (slow bullet & lock time) that provide a particularly tough added challenge.
Your ignorance is showing here. These shooters are shooting bullets weighing in at over 500 grains with multiple feet of drop and open sights. Your simply challenging anyone's opinion that doesn't support yours.