--- a/src/item_factory.cpp
+++ b/src/item_factory.cpp
@@ -221,7 +221,7 @@
         if( obj.ammo->loudness < 0 ) {
             obj.ammo->loudness = obj.ammo->range * 2;
             for( const damage_unit &du : obj.ammo->damage ) {
-                obj.ammo->loudness += ( du.amount + du.res_pen ) * 2;
+                obj.ammo->loudness += ( du.amount * 2 ) + ( du.res_pen * 2 / 3 );
             }
         }