I just started casting lead roundballs and have noticed a problem. I get lines in the roundballs. I think it's because my mould isn't hot enough but I'm not sure. I tried to heat it up but it didn't seem to help. Can anyone help?

Welcome to the forum carl. What kind of mold are you using. If it is one of the Lee's you need to smoke the cavities. Check out the directions. You may have a little oil on a new steel mold. Brake cleaner or carb spray cleaner works good to take that off.

If the lines stand proud of the surface, your mold might not be alinged correctly, and not closing completely. Might also be some kind of foreign material between the mold blocks that will not let it close.

If you mean circumferential wrinkles, that's a cold mould or alloy. If you are casting from a Lee pot, typically they won't get pure lead hot enough to cast good bullets. If you are casting on a stove with a standard pot, then turn up the heat. The advice to clean the mould with a degreaser is good as oil may be the problem, but this is usually seen as small bubbles or dimples on the surface of the bullet.