It's definitely the primo. There's a reason Schering left it at 100mgs/ml. It is very hard to compound 200mg/ml of primo. In order to do this many labs use too much BA which is probably the reason it hurts like a bitch.
I'm sure the feeling is very much like shooting T-400 (Denkall). Again there was a reason labs were not compounding more than 250mg/ml. They had to add too much BA which made life a bitch for us consumers.