Glad you mentioned it, I thought I was the only one who thought some ammo smelled funny that way.
I get that smell shooting Romanian 8mm surplus (corrosive 1970s stuff) and Golden Tiger 7.62x39.
What really struck me as strange was smelling some .223 I made last week using BL-C(2) powder - it had that same odd smell that I think now is ammonia-based. My other rifle loads I make with BL-C(2) don't smell that way, I'm wondering if the Remington SR primers I used might have anything to do with it?