I draw with a 21g, inject with a 31g. I simple swap the needle. To inject 50mg (1ml) of test cyp into my thigh (shallow IM I guess) takes me about 20 to 30 secs. The pressure in the syringe is high but if you make sure you're injecting slowly it works pretty smoothly. I don't get any bruises/soreness or any blood spilling.