diff --git a/data/json/items/gun/545x39.json b/data/json/items/gun/545x39.json
index 4fbf331163669..f77cd753992ec 100644
--- a/data/json/items/gun/545x39.json
+++ b/data/json/items/gun/545x39.json
@@ -78,7 +78,7 @@
       [ "stock", 1 ],
       [ "underbarrel", 1 ]
     ],
-    "flags": [ "NEVER_JAMS" ],
+    "flags": [ "NEVER_JAMS", "MISSION_ITEM" ],
     "weapon_category": [ "AUTOMATIC_RIFLES" ],
     "pocket_data": [ { "pocket_type": "MAGAZINE_WELL", "item_restriction": [ "ak74mag", "rpk74mag", "casket74mag" ] } ]
   }
diff --git a/doc/JSON_FLAGS.md b/doc/JSON_FLAGS.md
index 7ef483b166842..09f74ce311c8b 100644
--- a/doc/JSON_FLAGS.md
+++ b/doc/JSON_FLAGS.md
@@ -683,6 +683,7 @@ These flags can be applied via JSON item definition to most items.  Not to be co
 - ```IS_PET_ARMOR``` ... Is armor for a pet monster, not armor for a person.
 - ```LEAK_ALWAYS``` ... Leaks (may be combined with `RADIOACTIVE`).
 - ```LEAK_DAM``` ... Leaks when damaged (may be combined with `RADIOACTIVE`).
+- ```MISSION_ITEM``` ... This item's chance to spawn isn't affected by world item spawn scaling factor.
 - ```MOP``` ... This item could be used to mop up spilled liquids like blood or water.
 - ```NEEDS_UNFOLD``` ... Has an additional time penalty upon wielding. For melee weapons and guns this is offset by the relevant skill. Stacks with `SLOW_WIELD`.
 - ```NO_PACKED``` ... This item is not protected against contamination and won't stay sterile.  Only applies to CBMs.