diff --git a/src/CounterDrone.Core/Algorithms/DefaultDefensePlanner.cs b/src/CounterDrone.Core/Algorithms/DefaultDefensePlanner.cs
index 0ad63c3..8b7f2f3 100644
--- a/src/CounterDrone.Core/Algorithms/DefaultDefensePlanner.cs
+++ b/src/CounterDrone.Core/Algorithms/DefaultDefensePlanner.cs
@@ -178,10 +178,9 @@ namespace CounterDrone.Core.Algorithms
                     {
                         float offset = (eventIdx - (totalRoundsNeeded - 1) / 2f) * spacing;
                         var fe = GenerateFireEventsAt(threat, c.Unit, c.AmmoType, ammo, env, offset, yLane, yLanes, formationWidth);
-                        // 车道内序号 = 该车道已分配的弹药数
-                        int roundInLane = singleNeeded - laneNeeded[currentLane];
+                        int baseRoundInLane = singleNeeded - laneNeeded[currentLane];
                         foreach (var e in fe)
-                            e.FireTime = unitBaseTime + roundInLane * stagger;
+                            e.FireTime = unitBaseTime + (baseRoundInLane + ch) * stagger;
                         fevents.AddRange(fe);
                         eventIdx++;
                     }