Tell us about yourself!
If I remember correctly AB used the box fan and AC\Heater filter for drying herbs not protien
If you are using fired shotshells they your concerns about the primer are for naught.
Spent shotshell primers can be easily knock out with a small punch and hammer again only use spent (shot) shotshells
If you are worried about lead etc simple wash the shot shells in hot soapy water and then dry. It is important to use how water if you wash the shots shells because the "brass" of the shot shells normally is steel that has been brass washed so it can be prone to rust, hot water assures a quicker and complete drying.
Replace the plastic bottle with a new style aluminum bottle can or use a tin can and punch a hole in center of the bottom of the can and use a washer and a screw it to your "pole" and use a bottle with a screw on top