If your chin is sore, this is pretty uncommon. Usually it is the side of the neck and the collar bone that takes most of the pressure of holding the violin. Can you tell me more specifically where your chin hurts? Do you use a shoulder rest? If so, which one?
Personally I have a pretty flat chin rest. But I noticed on other violins that Ive tried, even a flat chin rest it’s not comfortable. I get red marks on my neck and collar bone. This can be totally avoided so why not avoid it?
I use a Strad Pad on my violin and have used one for years and years. The StradPad is a chin rest cover pad made of very soft foam. I also use a KUN shoulder rest. SuperiorViolins.com does carry the KUN Shoulder Rest, which is currently on sale. Click here to see it. Using these two items, I rarely have red marks or soreness.
I should also mention sometimes people jut the jaw out a little to hold the violin. This can cause the jaw to be tense and get sore. Maybe this is what you are doing? I’ll give you some tips on that if that is what you’re experiencing.