lol...I certainly have more than 1 pin....Does a bigger pin hurt more than a smaller pin ???
Yes it will hurt more because it is a larger needle so you are damaging more muscle. Don't worry about it, a 21G is a little large, but not much, it is fine.
And here is an post from Cy Wilson that will help you out with injections.
"Now, the injectable steroids are meant to be delivered intramuscularly, meaning, that you're going to have to inject relatively deep into the muscle. The "standard" needle is 22 gauge, 1.5 inch. This is used for injection into the buttocks. You can also use a smaller needle, like a 25 gauge, one inch, but it will take longer to inject and there's a chance you may not inject into the muscle fibers, depending on how much fat is on your ass. Generally though, most guys can get away with using a one inch needle. Also, you should take into account that although it will inject a lot faster, a larger gauge like 20 or below, will cause more pain and will damage more tissue.
The second most common injection site is the thigh. With this, you should only need a one inch needle. You can also inject into the shoulder as well as other places, but I'd prefer if you stuck with these two for now.
Okay, so now the question is, "Where exactly should you inject?" Well, if you're going to inject into the buttocks, you'll need to pick a cheek and then imagine a horizontal line beginning at the crack of your butt and extending outwards. Next, imagine a vertical line right down the middle of the first line. So now your butt cheek should be divided into four squares. The place to inject is in the upper most corner on the outermost section, i.e. the top right square.
For the thigh, a quick way to do it is to look at your hip and knee, and then imagine a line in between the two. This and a little bit lower are the areas you can inject. Make sure this is on the outside of your thigh!
Okay, so now you're ready. First thing? Wash your hands. Now find the spot, take a cotton swab and put some rubbing alcohol on it. Swab the area that you'll inject, then swab the rubber top of the vial. Grab the syringe and push it in at a 90° angle. (Some say to hold the needle like you're about the throw a dart.) Once the needle is fully submerged, pull back on the plunger just slightly and look to see if any blood enters. If it does, pull out and find a new place, as you've entered a vein and you don't want to inject into a vein.
If no blood appears, begin to push the plunger. Remember, the slower you push, the less pain you'll feel. Once the liquid is gone, pull the syringe directly out and apply a cotton swab to the site. Hold tightly for about 30 seconds and then either tape it on or put a bandage on it. Pull your pants back up; you're done!
Discard the syringe in a safe place and use a new one for the next injection. Never use the same needle twice (it'll be dull, plus you'll risk infection by reusing it) and, of course, never share a needle with anyone, especially if your training partner just happens to be a Haitian hemophiliac homosexual intravenous drug user."
