They were talking about the Challenge coin that was mailed to Anderson Cooper (see below if you haven't already). They talked to Bill Bratton who said they coins are usually about 2" and looked like it had been shot with a .22
I don't know how much Bratton knows, but if that coin is 2", the holes look to be just a bit short of 1/2" across (the ones in the center...the one to the left is broader, but might have had a wobble, or two hits really close). In my completely inexpert opinion, it looks like a 9mm or .40, but definitely not a .22 if the coin really is 2" across.
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