
Originally Posted by
Far from massive
21g is a larger diameter needle, a 25 gauge would be a smaller diameter needle. That said a 25 is about as small as you want to go since it becomes a pain in the ass to push gear through a smaller pin. If you are using a 23 by 1.5" needle for glutes you will probably want to use a 25 by 1" for quads, also the first couple of times at least I would split the shot in half and pin both quads as 3ml is a pretty large shot for quads and not one you want to start with first time out. When I use a 25 by 1 on quads I insert the needle about 3/4" into the quad and this provides adequate penetration, this varies depending on muscle mass and fat content.