[Slamdunkpro]

In reality your injection solution dictates your injector and needle size. If you have heavy or large particulate or a "chunky" injection you're going to be restricted to a manual type injector with a large bore open tip needle like a straight plunger or a Pistol syringe like a Heinki (they make all the pistol types including Spitjacks). If your injection is strained or or clear then you can use a draw type injector and smaller needles or needles with fine side ports.