I was just reading about the 37-mm 70K Naval gun that the Soviet Navy used for AA. I wanted to see how it compared to the Bofors 40-mm. These were both guns used on naval ships for anti-aircraft defense.
They seem pretty comparable, except possibly for one thing. Wikipedia says this:
One drawback was that the 70K required a barrel change after every 100 rounds fired. To improve on this, a twin-barrel water cooled mount, the V-11 (called "W-11" in East Germany and Poland because of different Cyrillic transliteration), entered service in 1946, and was in production until 1957. A total of 1,872 V-11 mounts were built.
There was no citation for it. But...ouch, a barrel change every 100 rounds?
Then I went to the Russian version of the 70K wikipedia article. It clarifies:
Охлаждение АУ было воздушным и являлось неудачным: так у 37-мм ствола с воздушным охлаждением длина непрерывной очереди составляла лишь 100 выстрелов по сравнению с не менее чем 158 у ствола с водяным охлаждением. После 100 выстрелов ствол с воздушным охлаждением либо следовало заменять (на что требовалось не менее 15 минут), либо ждать его охлаждения около 1,5 часов.
The cooling of the AU was air and was unsuccessful: for a 37-mm barrel with air cooling, the length of the continuous queue was only 100 shots compared to no less than 158 for a barrel with water cooling. After 100 shots, the air-cooled barrel should either be replaced (which took at least 15 minutes), or it should wait about 1.5 hours for it to cool.
Again, it is uncited. But it does offer clarification on a few things.
So now my obvious question is how does this part compare to the Bofors? What is the barrel change rate of the Bofors 40-mm gun? I did look for this on google with various keywords like "Bofors 40 mm barrel change" and "swap" and "overheat". It all came up nil. I hope someone here has a good idea on how to find this info.