The same thing happened to me when I bought my new bow. I am 29" Draw and shoot 71lbs. I picked the arrows I wanted and the guy went to the back and grabbed them. He never asked if I was running more weight out front or anything else. When he came out with 350 spine arrows I told him that I was pretty sure I needed 300 spine but he said "No, these are the right ones." I put brass in the front and he never mentioned that the spine might be weak. (I also realized that they didn't square the end of the shaft when I got home). I just went with it and when it came to paper tuning he could not get rid of a right tear. Which for a left handed person like myself, is a weak spine tear. I went home and as soon as I shot broadheads they were WAY off. Needless to say I gave those arrows to my dad who shoots lower poundage and will work good for him. I bought all new arrows in 300 spine and am building the arrows myself. I try to do as much work on my equipment myself, because even though I have never worked in a bow shop, I am pretty sure I know more about archery then they do, and I trust myself WAY more then the shops around me.