One Caliber Defender (Decaying Winter)

Perk: Sovereign
Traits: Reliable, Professional, Fearless
Equipment: Emergency Respirator
Challenge from Storm:
ONE CALIBER DEFENDER
A rough landing only motivates your desire for survival. Your only chance at an evac lies within the VIP pilot you were assigned to protect. As you grab your trusty equipment, you plan to fight until you're home safe. You believe that your obsession with your single caliber is all you'll need. Prove them right, agent.
In order to become a defender, holdout for reinforcements for 20 nights while only using one ammo type.
1) Reach and Beat Wave 20 individually on *Holdout mode.* (If you do not know how to start holdout, type /startholdout on the chat.)
2) Any perk can be utilized, with the sole exception of Hivemind.
3) Use of traits and auxiliary items are allowed. However, ladders are forbidden.
4) You must only choose one ammo type. Type out the ammo you will be using on the chat.
5) You may only buy two allies except for Ilija.
6) By the end of Wave 20, you must at least have 2000 salvage/scrap. You are not allowed to scrap items during the boss wave phase in Wave 20 and on Night 21.
7) You are not allowed to purchase the Chemical Station.