I use a 31g .5in slin pin for all oil pins, test tren deca whatever, in upper quads, for years also delts but usually hit upper quads, never gut, only slin and GH for gut pins, i also do sauna and spa everyday usually so it helps mitigate any redness irritation or soreness. good gear will flow through a 31g!!! I do .5cc to 1cc shots no issue. I also have a degree in phlebotomy and have ages of experience in the field doing shots and drawing/ only rookies use GSO still, sometimes I even pin the gh and slin in my abs, 10ius at a time for gh sometimes 1ml full, 10iu slin rarely , the ones dont sit as well but they're fine the next day. I use hepius labs from whats his name i cant remember on here sponsor Chinese dude AMAZING stuff