Comments by "Steve Valley" (@stevevalley7835) on "The Development of Ironclads - 1867 to 1872 in the Royal Navy - The Good, Bad and Useless" video.

@admiralrover74 the 14"/45 on the KGVs was really pretty ordinary. Muzzle velocity was 2483fps, vs 2458 for the 15"/42 during WWII. The 14" shell weighed 1590lbs vs 1938lbs for the 15" during WWII. And lighter shells tend to lose momentum faster than heavier shells, so, at distance, the 14" will deliver a lighter shell at slower speed. The only advantage to the 14" is it is a bit lighter, so more can be mounted on a ship. The same debate, more smaller guns, or fewer larger ones, raged in the USN during WWI.
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@admiralrover74 in general, that would be the case. I looked up the specific information for the 14"/45 and 15"/42, and it almost looks like the 14" was designed to replicate the performance of the 15", in a smaller, lighter package, rather than exploiting twenty years of advances in technology to produce a higher performance gun. The tables on Navweaps for these guns are expressed in degrees of elevation required to reach a specific range. For the 14": 13.75 degrees reaches 20,000yds, 19.25 degrees reaches 25,000. For the 15": 13.8 degrees reaches 20,000, 19.2 reaches 25,000. For the 14" striking velocity at 20/25K are 1563fps/1459. For the 15" @ 20/25k: 1556fps/1461. Angle of fall 14" @20/25K: 18.2/26.4. For the 15" @ 20/25K: 18.3/26.3. Armor penetration: 14" @ 20/25K: 11.2"/9.5" 15" @ 20/25K: 11.7/10.2". What was a 14" capable of in 1935? The USN rebuilt it's 14"/50s in the mid 30s and significantly improved their performance over their 1915 configuration. Performance of the rebuilt Mk 11 guns: range: 12 degrees yields 20,000yds and 17.6 gives 26,000 (not a typo, the tables do not give an elevation for 25K for an AP shell) Impact velocity (muzzle velocity was 2700) @ 20K/25K: 1588/1455. Penetration @20/25K: 13.75/11.27". Angle of fall at 20/25K: 16.33/24.8. According to the footnotes of the tables, the penetration data for both US and UK guns were calculated using a USN formula, so they should be comparable to each-other. Bottom line, for the typical BB armor belt of 13-14", the US 14" can penetrate at longer range than either British gun, and it's flatter trajectory will produce a wider danger space, improving the odds of a hit. The cost of the higher performance for the US gun is higher barrel wear due to the higher muzzle velocity, barrel life being on the order of 200 rounds, vs 340 for the 14"/45.
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@admiralrover74 Thanks to you for asking the right questions too. I just reviewed the deep dive KGV video again, and there is no discussion of the 14" being interoperable, in performance terms, with the 15" that armed 13 of the other 15 capital ships in the fleet. The documents cited simply handwaved away questions of an opponent being 2-3 kts faster, and dismissed questions about guns able to do decisive damage at greater range by saying that battle conditions may not always be good enough for the sighting systems to work at maximum efficiency. Official statements like that always leave me wondering what is not being revealed.
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@ramal5708 the M4 had a very low muzzle velocity. It was fine for plinking barges, but would not have had much range as an AA gun. In the 1920s, John Browning developed a 37mm AA gun for the army that had more potential. The original M1 version was clip fed. The later M9 version was fed via a metallic belt. The USN tested both the M1 and the Bofors, and chose the Bofors. which topped the M1 with both a larger shell and higher maximum altitude. Had the Bofors not been available, the M1 could probably have been developed into a serviceable naval AA gun.
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