I had a 25G needle and did my first test E pin into the quad, it didn't hurt much at the time, was sore like a motherfucker later. I had a shipment of 25G's that did not come in in time, and for the next pinning I used an insulin needle into the other quad. No pain, less sore, and the puncture mark resolved more quickly. It definitely got into the muscle, pressed flush against the skin. So now I am prepared to just use insulin syringes the rest of the cycle. Has anyone does this? and are there any concerns that I should have?