It's extremely poorly worded, as the word weapon is not the same as the word shell or ammunition. In fact, that's why we have separate words for both. I'd have thought people with English degrees (journalists still need education right?) would know these things.
But I'm not a journalist, so I guess they know best right? 😅
That's because british journalists are incredibly stupid. Industry standard is to refer to weapons by their bore–you don't call a Glock 19 a 185mm handgun, after all.