As you know, there is no collison in OOS so the only conclusion I can draw is that there is a chance when an OOS defender meets the Khaak that it will be able to obtain some sort of "critical hit", thereby killing the entire stack before they break out. Needless to say, this is a VERY good thing because : 1. You are not even informed of the encounter so you don't get distracted. 2. You don't get an endless stream of Betty warnings as your OOS ship starts killing the critters.
After watching this behavior over the months I've come to think that the chance of this "critical hit" (don't know what else to call it) seems to be related to type of ship that first intercepts the swarm. I have never seen a M3 or lower get lucky like this. A Nemesis will occasionally wipe out a "pregnant" Khaak M3 before it breaks into pieces. The Osprey *seems* to be slightly more successful than a Nemi. While capital ships do that with a fair regularity.
Since I don't know the guts of OOS combat, I can only guess that perhaps the ship's class has something to do with how likely it is for a one-shot kill. Another possibility is the number or types of guns that the OOS defender has. Since this is obviously a very desirable result, finding out how to maximize the chance for this "critical hit" will serve to make things run a lot smoother over the course of a game. Furthermore, if it turns out to be the total laser value that is the determining factor, then a ship armed with an otherwise very purpose-specific weapons like IonD would make an ideal OOS weapon.
All this assumes that it is not just my imagination.
