Thank you, chaps!
I'll first try the idea of grinding the ends of the pins to the desired radius. Should I persevere with my lathe and sharpening stone method, which clearly requires a fair bit of time and patience, or resort to something more brutal? The other idea I considered was the use of an electric grindstone and offering up the pin in a small chuck, which could be rotated. However, that latter would offer less control in terms of material removed. A pity that I don't have more than three of these pins at my disposal just now, as there isn't really any margin for error unless I get some more!
I'll first try the idea of grinding the ends of the pins to the desired radius. Should I persevere with my lathe and sharpening stone method, which clearly requires a fair bit of time and patience, or resort to something more brutal? The other idea I considered was the use of an electric grindstone and offering up the pin in a small chuck, which could be rotated. However, that latter would offer less control in terms of material removed. A pity that I don't have more than three of these pins at my disposal just now, as there isn't really any margin for error unless I get some more!