I am a IV fentanyl addict for 6 or 7 years now. I don't use a lot, and never increased my dose. You can only fit so much into a shot without the fent crystallizing in the barrel and clogging up. So I'm not able to make a big enough shot to do anything.
Taking one shot directly after another doesn't work either for some reason. If I do two shots back to back, I don't even feel anything from the 2nd one. It feels like there is a ceiling that I can't break thru. I just have a high natural tolerance on top of that. When I took vicodin pills before I was addicted, I would feel them much less than other people taking the same pills.
My stuff is not "pure," but it's high-grade street product directly from the source. I think if I had pure fent crystals that would be doable, but that is impossible to find, I am not very resourceful.
If I just were to quit for a week, to throw my tolerance, I could probably be free. Harder than it sounds though.
I have my eyes on a tank of inert gas from a welding company.