diff --git a/lib/cannery/ammo.ex b/lib/cannery/ammo.ex
index 26b0350..769e0b9 100644
--- a/lib/cannery/ammo.ex
+++ b/lib/cannery/ammo.ex
@@ -60,9 +60,10 @@ defmodule Cannery.Ammo do
       ) do
     Repo.one!(
       from ag in AmmoGroup,
+        left_join: sg in assoc(ag, :shot_groups),
         where: ag.ammo_type_id == ^ammo_type_id,
         where: not (ag.price_paid |> is_nil()),
-        select: sum(ag.price_paid) / sum(ag.count)
+        select: sum(ag.price_paid) / (sum(ag.count) + sum(sg.count))
     )
   end
 
diff --git a/lib/cannery/ammo/ammo_group.ex b/lib/cannery/ammo/ammo_group.ex
index 8b15224..97231ae 100644
--- a/lib/cannery/ammo/ammo_group.ex
+++ b/lib/cannery/ammo/ammo_group.ex
@@ -9,7 +9,7 @@ defmodule Cannery.Ammo.AmmoGroup do
   use Ecto.Schema
   import Ecto.Changeset
   alias Cannery.Ammo.{AmmoGroup, AmmoType}
-  alias Cannery.{Accounts.User, Containers.Container}
+  alias Cannery.{Accounts.User, ActivityLog.ShotGroup, Containers.Container}
   alias Ecto.{Changeset, UUID}
 
   @primary_key {:id, :binary_id, autogenerate: true}
@@ -24,6 +24,8 @@ defmodule Cannery.Ammo.AmmoGroup do
     belongs_to :container, Container
     belongs_to :user, User
 
+    has_many :shot_groups, ShotGroup
+
     timestamps()
   end