Ever since I saw Derek from more plates more dates’ video on why he only uses insulin pins, I only use 29 gauge 1/2 pins. I’ve pinned delts, ventroglute, dorsoglute, and outer quads many times with no issues hitting muscle. And I’m not lean at all…sitting around 20% BF at the moment. With glutes, where I have the most fat, to make sure I hit muscle, I push the syringe very firmly (but perfectly straight) into my buttock to compact the fat and get the needle into the muscle.
I will caution you though
Be very careful not to apply any lateral or shearing force to the syringe when pressing hard into your glute. You do not want that puppy snapping off into your fat. I use both hands to make sure I execute this very carefully.
Arguably the easiest method would be to just pin delts every day, as many do. I just personally prefer not to do this because it causes terribble acne on my delts and upper back. If you can get away acne free, or just don’t mind acne, delts are prob the easiest and safest.