No problem. That's what this website is here for. I always size my paint to the insert. That is one of the main advantages of a kit. I've used the same box of balls two weeks in a row and had to use different inserts because of the temperature and/ or humidity. On a rainy day I always go with a my biggest insert. It just tends to work better. If your barrel only came with one insert, you may want to consider buying more. They sell for about $12.50 (American). ActionVillage.com sells all the sizes!
