So the title says it all. I was under the impression it would be very obvious but I'm going to ask anyway just to ease my mind. When I pulled back on the plunger the blood seemed to "shoot" about .2-.3 units (20-30% of the barrel). The blood was also a bit lighter then usual (this was however only my third attempt). It didn't really look "frothy" or anything like that. I did have to pull back, the plunger didn't pull itself back. There didn't seem to be any pulsing to the blood and when I stopped pulling it stopped coming. When I pushed down there was a very small amount of pain. Does this sound like an artery?
I was only injecting saline solution.