Yup, I've done most of my pins with slin pins, test, eq, tren, mast you name it. No worries if you are getting IM. I thusly use pretty much bis, tris, delts and occasionally pecs
currently atttempting a cruise on 175mg/wk of test e and 60mg/wk deca for joints, and both are going thru a 30ga 1/2".. I also been seeing how subQ goes based off recent studies that were posted here and can say so far so good going into my 3rd week... also if your like me and cant stand the wait time drawing... I throw a vial in the microwave and nuke it for 15-18 seconds and the oil flows (almost) like slin... and no the crimp top dont spark etc either, my times listed using my spcific microwave are about the sweet spot on time... just be careful to not nuke too long or the oil/vial will get blistering hot in hurry and you may also get a burning smell from the labeling/ink on vial starting to overheat..
I think there has been research done with Deca and chickens and they injected deca into only one of the breast of the chicken and the breast tissue in the test subject did grow more muscle it was not just from having oil in the muscle. If I can track down the article I will post it up.
Have to be really lean or hit the calves, forearms, bi's, ect. The spot injection is only so you can hit different areas. It will not likely effect the growth of that muscle any more than another.
i tried shooting gear with slin pin and just dont have the patience for the oil to drip into the pin, if i had to choose between slin pin and 20g id would pick the Speer
I've been doing sub-q and IM using slin pins for months now. I have never had a problem with any oils loading a slin pin. It takes just about the same time as a 25 gauge pin. My arms have grown bigger, but I dont know for sure what is causing the growth, beit the spot injection or the oils.
try the microwave.. nuke vial for 15-20 sec (less time for lesser filled vial) and draws like using a larger gauge... never once had to bother with the backfill or any other method..