diff --git a/G.A.M.M.A/modpack_addons/G.A.M.M.A. Weapon Pack/gamedata/configs/magazines/weapons/w_mac10_mac18.ltx b/G.A.M.M.A/modpack_addons/G.A.M.M.A. Weapon Pack/gamedata/configs/magazines/weapons/w_mac10_mac18.ltx
new file mode 100644
index 000000000..9b3a4ac0c
--- /dev/null
+++ b/G.A.M.M.A/modpack_addons/G.A.M.M.A. Weapon Pack/gamedata/configs/magazines/weapons/w_mac10_mac18.ltx	
@@ -0,0 +1,18 @@
+; Magazine lookup fix for the G.A.M.M.A. Weapon Pack's MAC-18 conversion.
+;
+; The Weapon Pack converts wpn_mac10 from 9x19 (MAC-10) to 9x18 (MAC-18) via
+; mod_system_zzzzz_gamma_mac18.ltx, and its base_mac10.ltx rewrites the
+; [mac10_9x19] base type's caliber from 9x19 to 9x18 to match.
+;
+; However the weapon-magazine lookup (originally from 487- MAC10 Quality Control)
+; still only maps ammo_9x19_fmj to the mac10_9x19 base type. With the gun now
+; firing 9x18, there is no base_type binding for its actual ammo and the
+; magazine system skips the gun entirely.
+;
+; This file merges the missing 9x18 mapping into the existing [wpn_mac10] entry.
+; Filename starts with "w_mac10_" so it loads alphabetically after the upstream
+; w_mac10.ltx, ensuring the !-override targets a section that already exists.
+
+![wpn_mac10]
+;base_type for the MAC-18 (9x18) conversion
+ammo_9x18_fmj = mac10_9x19