[JBM]

Here is what I suggest you follow if you can.

http://rumford.com/K30plan.gif

Email Jim Buckly if you have more questions, he loves this stuff. Not that we dont, but I would like to see his throat system used to prevent any movement like you are mentioning. Short of that you need to build a throat with a bond break in it somewhere to ensure it wont move.

 

[JBM]

If you could use the Rumford throat it would solve your problems. The throat could be trimmed to fit if needed. The print says to use a 30" throat piece