Hi Endeavour. I had a core biopsy on one breast just over two weeks ago. I had the mammogram first to identity the position of my lump and then an ultrasound with the core biopsy. Honestly, it was more uncomfortable than painful, because I had to keep my arm up to allow access under my armpit. They did three biopsies, two of the lump and one of the lymph nodes and used local anaesthetic, making absolutely sure I could feel nothing before they did them. The actual biopsy didn't take that long but the preparation - precise location of the lump and setting everything up - took about fifteen minutes, I think. It felt longer but they did everything possible to make me feel at ease. I hope that helps and good luck for the mammogram. I hope everything goes well for you. 

I had my biopsy two days ago. It really didn’t hurt once they gave me the local anaesthetic. To be honest that hurt a little bit (like a pinchy scratch) after that I didn’t feel anything painful. I took a stress ball to squeeze. That helped me! The nurse pressing hard on my biopsy site afterwards to help reduce the bruising was uncomfortable but not painful. It was a bit achy afterwards but paracetamol helps. 

Hope yours goes smoothly  

although I have to now wait for my results I’ve been told it’s a 2cm lump and should be easily dealt with.