If it doesn't fit, get a good caliper or a 1" micrometer and measure the pin diameter. Then wrap the top in one layer of masking tape or electrical tape, chuck it in a drill press, and take it down with #320 or finer emery cloth. Take it down about .001" at a time, and check the diameter at several places to assure a constant diameter. When it finally fits, take it down another thousandth, clean it and cold blue the portion you worked on.
Edit... Ideally it should be centerless ground; second choice is a lathe - but I figured you don't work in or have access to a machine shop, so the drill press is the way to go.
Edit... Ideally it should be centerless ground; second choice is a lathe - but I figured you don't work in or have access to a machine shop, so the drill press is the way to go.