TBH I myself feel that a 57mm gun is either too much gun, or too little gun. They tend to be big enough and displace enough to require a mounting space that could take a 76mm or 127mm gun, but have a weight of shot that tends to be low enough as well as shorter range to limit the effects of that shot. Also whilst the guns might have reported high ROF, in reality those ROF claims tend to be overestimated calculations which ignore the gun mounting/ready round ammunition capacity. It is rather difficult to achieve a 220 RPM ROF via a Mk 110 57mm gun that can only hold 120 ready rounds two sets of two 20 round cassettes which replenish the ready rounds from the magazine via a hoist.
I think part of that is the US invested a lot into the 57mm gun for the LCS program.
Part of saving face is using that gun. It is a fine 57mm gun, and on small aluminium ships, was big enough. The 57mm gun may find its way as a secondary on larger US ships in the future, like carriers, LHDs, LPDs, perhaps even destroyers. There is nothing really wrong with the 57mm, except that it 57mm. Like all US projects the 57mm is supported locally, and becomes a political program as well as a military one.
They are spending a bunch of money to make the caliber more lethal.
PLYMOUTH, Minn. – Oct. 4, 2023 – The U.S. Navy has awarded Northrop Grumman Corporation (NYSE: NOC) a development contract for the company’s newly designed 57mm guided high explosive ammunition. Designated for use with the Mk110 Naval Gun Mount, the...
news.northropgrumman.com
Also the US has plenty of other options in terms of hitting targets. Unlike smaller navies. If working with destroyers, the 57mm gun provides a nice in between caliber between 5"guns on destroyers, 20mm and 30 mm CIWS on other ships. Its the USN, a 57mm gun isn't going to single handled take on the Chinese navy. When you have ~70 large destroyers, a dozen carrier groups, you start looking at niche capability. The 57-76mm category seems quite interesting given the drone threat in the red sea. Enough power and range to keep it further from the ship, cheap to fire, fast rate of fire, but limited overkill, some of them are operating near shores etc where firing many 5" rounds into the sky at a drone is going to cause a lot of damage on the ground, or potentially to other shipping, its a busy area, having 25km range is bad in that context.
Part of the issue with the constellation was to make them different to the Burkes. If they fitted a 5" and 64VLS, you have effectively replicated a burke on a different hull. 57mm production was already there, 32 VLS is significant, but significantly different from a burke. The ship is going to be way more useful than the LCS ever could be, and much more like the very popular FFGs, which had a light 76mm gun (think back to the 60's and 70's when these designs were happening 76mm was light weight!), and a useful amount of missiles, efficient in cost, but also clearly multirole flexible platforms that complimented the more powerful, more focused US platforms of the 60/70/80s.
This is clearly an issue we have with the tier 2 and tier 1. Can I see Hunter being fitted with a heavier fitout, sure, closer matching a Burke, but with much lighter crew requirements, more fuel efficient, more Australian content. I expect flight II to have 64 or more VLS, and flight I may be refitted with that at a later date.
Tier 2 probably maxes out at 32 VLS, yeh tactical length could be an advantage here, as it clearly sets boundaries on what the platform is. Its about self defence. Meaning these also become less of a target, if you can't launch long range weapons, it means you are not going to be the first target the enemy tries to take out. 32VLS is a heavy self defence capability. China has a lot of missiles, but not enough to launch them all at every target. Tier 2 gets tier 2 weapons, which are shorter ranged and smaller generally, and probably in less numbers.
Drone ships, subs, destroyers are strategic launch platforms. They are either more expendable (drone ships), or more capable (destroyer) or more stealthy (subs).
Really with TLAM, which is a bulky, non-stealthy, slow, heavy, cruise missile, subs are really they only viable platform. Because any surface ship will be seen coming 1000nm away. Its no longer the 1940's when you needed search planes. Or even the 1970's, when you recovered film dropped by satellites. IMO subs offer the only viable launch platform for that munition in the 2020+ timeframe. Even then, you are going to be firing them in large volleys, like 16-24 at a time, not something a tier 2 combatant can do. Also once the war begins, I think TLAM is pretty useless. Its key advantage is range, so is good at surprise surgical strikes, particularly against undefended or lower tech targets that aren't hardened or protected. If launched in big waves of dozens, then it has the ability to overwhelm targets at huge range, allowing the US is focus its firepower on a small selection of targets and fight its way through defenses, with minimal risk. A SSGN fires 128 TLAM, completely by surprise, over 1000nm away, yeh, effective, and you are never seen. A 6000t frigate fires 2 TLAM 500nm away, and you have just made yourself a target.
Australia is never going to be able to do that, alone, overwhelm and fight through defended positions.