If interested in Live Center Creative Inventions make them out of brass you can fine them in Mueller Billiard Catalog.
I had a set like those from Brianna and they worked fine for the butts and larger pieces, but when doing shafts, I have ran into them. Being brass helped as it didn't damage the cutters, but did take chunks out of the brass. The type of longnose these type have are about a 1/4" dia. for about 3/8" then taper gradually giving more wiggle room for the cutter.
I made a new nose for the Brianna one out of brass and then re-pressed it together. It gave the clearance I wanted, but has about .003-.005" runout so I don't use it. I should have used new bearings when I pressed it back together.
Dave