actually you are most likely wrong my friend. yes prop esthers are more painful and yes you can get an anti-histamine effect. but neither are what I experience with sustanon, its a totally different pain my friend than the pain you get from tren ace.. TOTALLY different.... sustanon prop ? its a VERY small amount in that compound, silly to blame it on that. its mostly long esthers. I have a very good thread up about painful injections and what causes them that I put up a month or two ago
http://www.elitefitness.com/forum/anabolic-steroids/injection-site-pain-facts-tips-746003.html
BA is one of the main factors, atleast with sustanon.
primo has the high concentration the fellow before me was talking about. primo is painful going in and if you dilute you are only gonna have to end up injecting more oil.. huge pain in the 'ass' literally. but its NOTHING compared to the hell that you will get injecting a large amount of sustanon, not even in the same league.