The normal decapping pins are 2.0mm, or about .080" in diameter, and that's what you'll find in the vast majority of dies out there now, at least in most cartridges. There are some accuracy oriented cases, however, that use a smaller 15.mm or .058" flash hole. Our 220 Russian, 6mm BR and the new 308 Palma are good examples of this. RCBS makes decapping pins for this diameter hole, and it should be their part number 9608. If you speak to them, just tell them it's the small pin for the 6mm BR, the PPC or the 220 Russian, and they should steer you onto the correct one. Graf's here in MO should also carry these. Wouldn't surprise me if Bass Pro might have them as well.
Or, as Russ said, you could just polish down the existing pin, it doesn't take much. I'd go ahead and order the correct ones, though, trust me, having extra decapping pins on hand is ALWAYS a good thing.
Kevin Thomas
Lapua USA