After my $20 floor pump from the hardware store gave out. I bought a rather more expensive one rated to 160 PSI. The pump has a metal nozzle on it, with a Schrader opening on one end and a Presta opening on the other.
I find closing the Presta side of the nozzle requires an extremely large amount of force. It seems like I get a much tighter seal with it, and that I can go to higher pressures as a result. However, because it requires so much force to close I have ended up bending the valve stem every time I use it. Ultimately I've gone back to using the Schrader adaptor I had for the old pump, along with the Schrader side of the nozzle, which is much easier to close.
Is there a trick to closing a purpose-designed Presta nozzle? Is my pump defective somehow?