I have heard from others that you shouldn't use hot water to heat your oils. I don't actually remember the reason why, but I also Believe
@Stanfordpharma1 has mentioned this before as well. A lot of guys including myself use a small candle warmer and place your vials on to heat up your oils, then draw and pin. I've also sat my syringe on the heater duct in my bathroom for a bit while the heat runs and warms the house up in the morning, but that only works in the winter months. Once its warm it should pin very smooth, at least in experience.