diff --git a/L2J_Mobius_1.0_Ertheia/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java b/L2J_Mobius_1.0_Ertheia/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java
index d98d83bb9b..11ed0bc5a0 100644
--- a/L2J_Mobius_1.0_Ertheia/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java
+++ b/L2J_Mobius_1.0_Ertheia/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java
@@ -689,12 +689,13 @@ public final class L2NpcTemplate extends L2CharTemplate implements IIdentifiable
 	
 	public Collection<ItemHolder> calculateDrops(DropType dropType, L2Character victim, L2Character killer)
 	{
-		final List<DropHolder> dropList = getDropList(dropType);
-		if (dropList == null)
+		if (getDropList(dropType) == null)
 		{
 			return null;
 		}
 		
+		final List<DropHolder> dropList = new ArrayList<>(getDropList(dropType));
+		
 		// randomize drop order
 		Collections.shuffle(dropList);
 		
diff --git a/L2J_Mobius_2.5_Underground/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java b/L2J_Mobius_2.5_Underground/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java
index d98d83bb9b..11ed0bc5a0 100644
--- a/L2J_Mobius_2.5_Underground/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java
+++ b/L2J_Mobius_2.5_Underground/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java
@@ -689,12 +689,13 @@ public final class L2NpcTemplate extends L2CharTemplate implements IIdentifiable
 	
 	public Collection<ItemHolder> calculateDrops(DropType dropType, L2Character victim, L2Character killer)
 	{
-		final List<DropHolder> dropList = getDropList(dropType);
-		if (dropList == null)
+		if (getDropList(dropType) == null)
 		{
 			return null;
 		}
 		
+		final List<DropHolder> dropList = new ArrayList<>(getDropList(dropType));
+		
 		// randomize drop order
 		Collections.shuffle(dropList);
 		
diff --git a/L2J_Mobius_3.0_Helios/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java b/L2J_Mobius_3.0_Helios/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java
index d98d83bb9b..11ed0bc5a0 100644
--- a/L2J_Mobius_3.0_Helios/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java
+++ b/L2J_Mobius_3.0_Helios/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java
@@ -689,12 +689,13 @@ public final class L2NpcTemplate extends L2CharTemplate implements IIdentifiable
 	
 	public Collection<ItemHolder> calculateDrops(DropType dropType, L2Character victim, L2Character killer)
 	{
-		final List<DropHolder> dropList = getDropList(dropType);
-		if (dropList == null)
+		if (getDropList(dropType) == null)
 		{
 			return null;
 		}
 		
+		final List<DropHolder> dropList = new ArrayList<>(getDropList(dropType));
+		
 		// randomize drop order
 		Collections.shuffle(dropList);
 		
diff --git a/L2J_Mobius_4.0_GrandCrusade/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java b/L2J_Mobius_4.0_GrandCrusade/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java
index d98d83bb9b..11ed0bc5a0 100644
--- a/L2J_Mobius_4.0_GrandCrusade/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java
+++ b/L2J_Mobius_4.0_GrandCrusade/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java
@@ -689,12 +689,13 @@ public final class L2NpcTemplate extends L2CharTemplate implements IIdentifiable
 	
 	public Collection<ItemHolder> calculateDrops(DropType dropType, L2Character victim, L2Character killer)
 	{
-		final List<DropHolder> dropList = getDropList(dropType);
-		if (dropList == null)
+		if (getDropList(dropType) == null)
 		{
 			return null;
 		}
 		
+		final List<DropHolder> dropList = new ArrayList<>(getDropList(dropType));
+		
 		// randomize drop order
 		Collections.shuffle(dropList);
 		
diff --git a/L2J_Mobius_CT_2.6_HighFive/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java b/L2J_Mobius_CT_2.6_HighFive/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java
index 333772b30d..850fc326a4 100644
--- a/L2J_Mobius_CT_2.6_HighFive/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java
+++ b/L2J_Mobius_CT_2.6_HighFive/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java
@@ -95,8 +95,8 @@ public final class L2NpcTemplate extends L2CharTemplate implements IIdentifiable
 	private Map<AISkillScope, List<Skill>> _aiSkillLists;
 	private Set<Integer> _clans;
 	private Set<Integer> _ignoreClanNpcIds;
-	private CopyOnWriteArrayList<DropHolder> _dropListDeath;
-	private CopyOnWriteArrayList<DropHolder> _dropListSpoil;
+	private List<DropHolder> _dropListDeath;
+	private List<DropHolder> _dropListSpoil;
 	private double _collisionRadiusGrown;
 	private double _collisionHeightGrown;
 	
@@ -546,12 +546,13 @@ public final class L2NpcTemplate extends L2CharTemplate implements IIdentifiable
 	
 	public Collection<ItemHolder> calculateDrops(DropType dropType, L2Character victim, L2Character killer)
 	{
-		final List<DropHolder> dropList = getDropList(dropType);
-		if (dropList == null)
+		if (getDropList(dropType) == null)
 		{
 			return null;
 		}
 		
+		final List<DropHolder> dropList = new ArrayList<>(getDropList(dropType));
+		
 		// randomize drop order
 		Collections.shuffle(dropList);
 		
diff --git a/L2J_Mobius_Classic_2.0_Saviors/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java b/L2J_Mobius_Classic_2.0_Saviors/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java
index b87e1d3dbb..6817d54b50 100644
--- a/L2J_Mobius_Classic_2.0_Saviors/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java
+++ b/L2J_Mobius_Classic_2.0_Saviors/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java
@@ -689,12 +689,13 @@ public final class L2NpcTemplate extends L2CharTemplate implements IIdentifiable
 	
 	public Collection<ItemHolder> calculateDrops(DropType dropType, L2Character victim, L2Character killer)
 	{
-		final List<DropHolder> dropList = getDropList(dropType);
-		if (dropList == null)
+		if (getDropList(dropType) == null)
 		{
 			return null;
 		}
 		
+		final List<DropHolder> dropList = new ArrayList<>(getDropList(dropType));
+		
 		// randomize drop order
 		Collections.shuffle(dropList);