X-outs can be nearly any defect.  In this case, it appears it may have been a total weight flaw that is going to make it a bit problematic, but not too bad.

 As long as you drill enough weight out that it weighs 16lb or less after drilling you should be fine.

 Depending on how the manufacturer does it, the .3 part could be either 3oz, or as much as 4.8oz.

 3oz is not hard at all, but 4.8 could be problematic. Make sure and weigh it out before drilling to know exactly what you are trying to do.