I guess I should detail how I tested. For the record, I am on RC7; I don't think that affects anything though.
As I mentioned, I first saw it (but wasn't sure) on Saturday while testing a triple Typhoon Harbinger (no combat skills) against the sim Onslaught. The three Reapers would sometimes take the Onslaught to near-dead with one volley.
This evening, I took the Ambush mission's Afflictor, loaded it up with 4 Reapers and EMR, and killed the sim Onslaught with it by flanking to the rear. Never used the ship system.
I did this like 10 times. Usually it took 7-8 missiles as you would expect (1 or 2 get shot down sometimes). Twice, however, the first volley of 4 missiles was enough to destroy it.
With more controlled conditions (disabling the target's AI, using one of those meat-block ships in that testing mod, etc.), the effect can probably be observed with other weapons.
Okay, tested twice more as above while writing this and killed it with 5 Reapers both times. I'm going to keep testing.