I need some help from some more experienced reloaders.
I'm necking down Fed 300 Rum brass to 7mm Rum and I'm getting terrible amounts of runout no matter what I do. This is my first trip at necking down to another cal so any suggestions would be much appreciated.
I'm using a Redding neck die with expander ball. I'm using plenty of lube in the neck area but not too much. Would I be better to use a collet/bushing style die??
What can I do??

You can start the cartridge into the die and when you get about a third of the neck squeezed down back off and rotate the case 1/3 of a turn. Then resize another third, back off and rotate another third and then resize it all the way. Sometimes this makes them more uniform.

If the mentioned technique doesn't work then perhaps you should consider a forming set that takes the neck down gradually. I personally would expect to be able to go down to 7mm from 30 in one easy pass. I often use the trim die for the desired caliber to "form" the case and then run it through a full length size die.
For this I prefer the RCBS trim dies.

I do use Imperial size die wax for forming now instead of regular case lube. I don't get oil dents with this.

For real problem cases I use a Redding body die with neck size bushings of gradually decreasing size.

Is the shell holder base barring surface perpendiccular to the line of action in the die? Are you expriencing any bending moment at the end of your stroke? ( No pun intended).

Take your dies over to a reloading Buddy and try his set up; his shell holder also. If your equipment is any good you shouldn't have to rotate. (Again no pun intended.) roger

Runout immediately after necking down is very common and there's not much you can do about it. Once you fire form the case the runout will disappear. Problem is that when the mouth of the case enters the constricted part of the die there is no support by either the die or the shellholder for any part of the case. A portion of the neck may constrict unequal to another side, the rest of the neck follows and the neck is stovepiped. Same thing happens in expanding necks up a caliber or two.

Fire form your cases either with a fast pistol powder and a filler or with cheap bullets. They'll straighten out. Sometimes it takes two tries but usually not.

Thanks guys! I was not sure if it was normal for the runout during sizing down. Some cases that I have done so far don't show the runout but some are bad. I guess I will load em up with a medium load and shoot them and check again.
Thanks for all the help!

Any time you reduce the dimentions of a fired case by a significant amout you'll get lotsa runout. the only way to avoid runout is to use a die that reduces dimentions by .001" only or have a chamber that is .001" over virgin brass.

What Bob338 said, fire them 1st then worry about runout. I find I have better luck necking up one size than necking down one.

Thanks for the help guys. I loaded and fired 20 of the cases that I had necked down and after firing the runout was gone.
Thanks again for the help to all of you that replied!!