As weird as it sounds yes I have seen this posted online before. On one hand it almost makes sense, as the premise is rubbing stuff together to polish it, and what reloader doesn’t have a near infinite supply of spent primers on hand?I am not doubting you, but really? Why? I hate the residue from primers I have decapped. I am curious as to the rationale. I guess they can’t plug the primer hole. I am ashamed to admit I don’t know what the metal is but has to be harder than the brass?
however it is foolish, as has been experienced by @awshoot. I don’t know if maybe they were smashing them? But not something I will ever attempt as we now have first hand experience that it not only doesn’t work but also defeats any savings.