Journals (science, history, etc) are extensively peer reviewed, and are published in print, as well as online.
You can't always trust printed material either though. Writers and editors can and do make mistakes.
I don't know if explosive rounds were standard load-out on subs, but they did exist. Size apparently wasn't much of an issue, as timed fuses were implemented in rounds as small as 20 mm. I'm sure each round was expensive to produce, but they managed.
If by chance they were carried as part of a sub's AA armament, then it would be nice to see a mod which includes them.