I see you are a writer, and I am not a pro writer, but I disagree.
I’m not a reporter, but for years I listened to one on the radio. A VERY successful reporter named Howie Carr. He taught me that good reporters get the basic facts. In this case, the caliber of gun is one of those facts. It’s both interesting and pertinent.
& btw, did you notice a reader wondering about that very fact? That is because it IS interesting and pertinent, and the reporter left it out. The correct response is not, ‘Nobody should care!’. It is, ‘Obviously some readers care, and since the fact would have been simple to ascertain and not at all space-consuming, it should have been included.’