Hello,
I have to disagree. Woodcraft's bushings are garbage. When I used their bushings for the circuit board Wall Street, the pen turned out out od round. Ditto for Navigators and Sedonas. My recomendation would be to use a micrometer to measure, then if they match use your sierra bushings, otherwise turn without bushings and measure regularily.
Dan
I'm having a little trouble envisioning how a bushing could result in an out of round pen. I'm probably just not thinking right.