I have never been a fan of deep injections, as I have always been of the school of thought that if it is in the muscle, it is an effective IM. regarless of being .5" deep or 1" deep.
Someone correct me if I am wrong on that, or if that can lead to problems.
My normal protocol has been this:
I always swipe the top of the vial with alchohol, and the the site I will be injecting before doing anything else.
1. Load the syringe with an 18 gauge pin.
2. Leave one tiny spot of air at the top of the syringe, by pulling back on the plunger just slightly. And change out the needle with a smaller 27 (sometimes 25) gauge that is only .5" long. Push out that tiny bit of air, so that I see just one ity bitty drop of the test coming out the tip of the needle.
3. inject, nice and slow. Wait several seconds at the end before withdrawing the needle. For some reason that seems to prevent any leakage.
4. I do not put any more than 1 cc in any one spot. If I need to shoot more than that, I then replace the needle with another .5" 27 gauge, and stick another spot. (Do I need to be switching out the needles when doing this? Or is it safe to pull out and re-inject with the same needle?)
This is what I do when hitting tris, delts, or quads, as I know I do not have much fat covering any of these areas, and I have never seen a bubble under the skin from doing this either.
Should I be going a full 1" deep instead? Does that help anything really? Or is these just some anecdotal evidence that deeper get absorbed faster?