I have only used my shoulders and legs. I normally use a 22/23 guage if I have really good quality win. Otherwise, I use a larger pin as it clogs to quickly.
But I started using about a 1/4 cc of test in the syringe. I draw up the winny, then draw up the test, stick and start injecting. As long as you keep steady pressure the winny will flow like a champ. Just be prepared for the winny to shoot in much faster as it is water based and not oil like the test. It will startle you as the shot transitions from one to the other.