I've got a Park Tools floor stand pump that works great, except on smooth road tire valve stems, which tend to pop out of the clasp when you approach 100 psi. This doesn't happen on the threaded stems. The guy at the LBS where I bought the pump suggested holding the clamp in place while pumping, but as much as I hate to admit it in a public forum, I'm not strong enough to pump to 100 psi with only one arm. Well, I can do it, but it ain't pretty.
Anyway, I found that by scuffing up the valve stems with a piece of coarse sandpaper, it creates enough rough surface area to hold the pump clamp in place.
If that violates some rule of biking etiquette then I apologize in advance. It doesn't look bad--more like brushed stainless or aluminum than anything else. Goes with the brushed aluminum finish on my Giant.