I keep saying I want to read every single SCP before I make a new one, but after 3 years I realized that wasn't feasible.
My idea is, basically, a rifle from the Spanish Civil War with "esta maquina mata fascistas" engraved into the butt, like many did during the war.
The anomalous properties of this SCP come into play when an individual fires it at another person. If anyone who is subordinate fires it at someone with any degree of authority, that authority figure will die. Conversely, if an authority figure fires it at a subordinate, the projectile is rendered harmless.
Basically, the SCP takes "fascist" to its most extreme definition. I have in mind a series of tests wherein D-class are given arbitrary "promotions" to test the efficacy of the weapon, and the parameters by which it functions.