I just used a slin pin. Walmart. $8.
Even a 1cc is easy to read. They come smaller if need be.
1cc = 1ml In this case, 50mg = 1cc (1ml). The mg/ml is dependent on the concentration.
A TB needle is a tuberculin pin. You can get a slin pin, smaller guage, both 1cc, for about $10 less per 100 than a TB pin, most places.