I've found that Lee moulds leave a less pronounced sprue than Lyman, but all cast balls will have a sprue. I've also found that positioning of the sprue when loading doesn't have a very dramatic effect on accuracy. Put fifty or so in a rotary tumbler for 20-30 minutes and the remains of the sprue will be virtually undetectable. Of course, they look like miniature lead golf balls when you're done, but, once again, I don't see any adverse effect on accuracy.
Sometimes the squeaky wheel gets replaced...