This item is not included in any spawn asset, but it doesn't necessarily mean that it doesn't spawn naturally on any of the maps.
12g_12_Gauge_AP-20_Slug_2rnd_Ammo_Belt.dat
GUID 1cfd88a69b6f452d888d2018c5824898
Type Magazine
Rarity Rare
ID 35802
Size_X 1
Size_Y 1
Size_Z 0.1
Amount 2
Count_Min 2
Count_Max 2
Calibers 1
Caliber_0 35072
Ballistic_Damage_Multiplier 6
Spread 0.3
Tracer 55
Blueprints 5
Blueprint_0_Type Ammo
Blueprint_0_Supplies 1
Blueprint_0_Supply_0_ID 119
Blueprint_0_Build 30
Blueprint_1_Type Ammo
Blueprint_1_Supplies 1
Blueprint_1_Supply_0_ID 35047
Blueprint_1_Build 30
Blueprint_2_Type Ammo
Blueprint_2_Supplies 1
Blueprint_2_Supply_0_ID 35802
Blueprint_2_Build 30
Blueprint_3_Type Ammo
Blueprint_3_Supplies 1
Blueprint_3_Supply_0_ID 35801
Blueprint_3_Build 30
Blueprint_4_Type Ammo
Blueprint_4_Supplies 1
Blueprint_4_Supply_0_ID 36331
Blueprint_4_Build 30
Use_Auto_Icon_Measurements False