A quick little story: A customer called and complained he could not extend his short shank burs out as far with the new chucks VS the old chucks in an electric motor contra angle (kavo 25lca) !!!! Please listen close, never, never, run any bur in any highspeed unless it is fully seated in the chuck. (you don’t want it to come out at 300,000 rpm do you?) Monitor the wear on your chucks by inserting a bur and try to pull it out with your fingers, if you can, the chuck needs to be replaced. This is not an area to live on the edge.