Half inch 30 gauge syringe.

Lats, traps, and delts. Kind of a pain in the ass to push the oil through that small gauge syringe. But you don't feel a thing.

1 in Long 25 gauge for glute medius. Least pain with no issues.

You might be hitting scar tissue, so more injection sites might help. But the first few times you pin a new area it will hurt and that spot. Virgin muscle.