Prop doesnt hurt. Its the way the stuff was made. Too high of a concentration of BA. "prop pain" is a myth in my opinion. I have used 200 mg/ml, i have used prop from several batches where i controlled all the variables like kind of oil, ba and bb amounts and have never had a problem.
So my recomendation for your badly made gear problem is rub it very hard right after you pull out the pin. I've read about guys using a massager or a heating pad.
The only thing that really hurts is winny, and the only thing that fixed it for me was a lot of pressure on the inj site,