Hey bro,
Alot of people here are probably going to tell you not to do it. I usually use the same pin for drawing 2-3 times. Before I store it I fill the old barrel with air and push it through the pin to blow out the left over oil then I wipe it with an alcohol swab and place the cap back on it.
I do the same thing when i'm ready to inject again, I get my new barrel and fill it with 3cc of air then I put the drawing pin on and push the air through it again and finally swab it with alcohol.
It probably is stupid seeing as though needles only cost $9.00 per 100.