I'm with dma on this one get 1", I use 1.5" for glutes but it's also because that's what my doc prescribed me 23/25 guage.
I have to disagree with not using an 18 to draw. unless your supplier has cheap building materials... I have never had an issue drawing from my vials at a 1/2 cc consistently with it never leaking from a 10ml vial. I am also extremely impatient that's why I draw with an 18g and I'm extremely patient with injecting haha that's why I use a 25g normally. Also DO NOT PINCH the area you're going to inject into it makes it more painful, just slight stretch the area and make sure you've removed the weight from the leg that you're injecting into the glute, makes for a smoother poke.
Invalid Link Removed18g needles are too big and they will eat up your stoppers in a hurry. A bigger hole means an increased chance of letting some little nasties into your sterile vial. Sometimes, the 18g will take out little chunks of rubber that fall nicely into your vial. That is not something you want. Imagine injecting that tiny piece of rubber into your muscle. I'll bet the doctor would have lots of fun digging into your rmuscle trying to find it and mutilating your muscle in the process.....