Modern naval guns larger than 130 mm

It is apparently very, very hard to develop a naval gun of greater than 130 mm calibre and get it deployed on warships - and has been so for sixty years. The desire for a big gun is widespread, but one project after another fails.

The typical naval guns with ship-to-ship fires in mind are of 57 to 130 mm calibre, but nothin below 100 mm calibre is taken seriously as a munition for doing structural damage or opening the targeted hull for the sea.
In fact, historical experiences from late 19th century up to the Second World War proved that guns weaker than 138 mm calibre* were disappointing in surface actions. The first calibre proven to be satisfactory for surface actions was 149 mm, and it's likely safe to say that with improvements in shell quality nowadays the historical 138 and 140 mm calibres would prove successful as well. This is a quite most point though; the adoption of the ground forces calibres of 155 mm (NATO) and 152 mm (Russia, PRC) is the only sensible choice for a conventional large calibre naval gun.

Historical attempts to build large calibre naval guns included the 8" L/55 Mk.71 of the USN, followed by the 155 mm L/62 AGS and an even more ambitious, expensive and difficult rail gun project. Germany tested an improvised solution of 155 mm calibre.

There are several problems; gun stabilization (not harder than with other naval guns), saltwater exposure (this was troublesome for the German MONARC project apparently), volume and mass of ammunition in the magazine, mass of the gun system (metacentric height of the ship!) and ammunition feed from magazine to gun.

I don't think any navy absolutely needs big guns, but it's a striking example for how well-funded navies strive for 90-100% solutions and fail, usually getting nothing in return for decades - not even a 70% solution.

Here I'll show how simple and cheap this could have been had in my opinion:

Navies used to employ simple single 6" gun mounts on protected or light cruisers,
and this would still be effective in surface actions with automated gunlaying

(1) take a gun laying and stabilization system from an existing 100-127 mm naval gun turret
(2) build this gun again (or a similar one), maybe with chamber dimensions changed to the specs of army 155 mm howitzers
(3) mount it for a maximum elevation of about 18° to 43° - a turret or shield is optional
(4) install it on a ship, control it with an existing fire control computer fed with correct ballistic data, with different charge settings for choice.
(5) use 155 mm shells type-classified by the nation's ground forces already.
(6) store the ammunitions below the waterline in a lightly armoured compartment with appropriate (standard) cooling and fire extinguishing/rapid cooling installations.
(7) ammunition supply with a simplistic lift that moves pallets of each four shells + propellants, manual handling at the magazine and between lift and gun. Submarines succeeded in manually supplying shells to an exposed gun barely above waterline during both World Wars.**

Estimated time till prototype works well: One year.
Estimated time till certified: Another year.
Estimated program budget: € 30 million for eight ships equipped with one gun each,
including 15% profit for contractors.

The barrel length and muzzle velocities of this gun were almost identical to current 155 mm L/52 howitzers.

There is absolutely no need for automatic loading and thus no need for a high capacity ammunition feed, elaborate turret etc. because 155 mm is still in the weight range which allows for rapid manual loading - particularly if you give the crews modern strength and endurance training. The rate of fire could drop below 5 rpm for gun high elevations unless the power operation of the gun quickly depresses the gun for the loading drill and quickly elevates it again for the shot. I suppose 4-6 rpm, the rate of fire of late Cold War 155 mm howitzers, would be realistic.

Destroyers equipped with one such relatively simple mount (open, shielded or in a turret) would be capable of noticeable naval gunfire support, and could engage ships out to the horizon with it as well. Small and fast craft could be engaged at several naval miles range electronic using time fused HE shells.

Naval gunfire support and naval gunnery aren't really important topics, particularly not for Europe's defence. Still, the example exposes (in my opinion) systemic failures by Western naval bureaucracies. It would take a competent, "energetic" and stern political leadership to push these bureaucracies into failing less and getting things done better with less.


*: 138 mm was used on board of French large destroyers and 140 mm onboard of old Japanese light cruisers and some old Royal navy ships. Neither calibre saw much action, thus not proving itself. Common light cruiser calibres of WW2 were 150 and 155 mm (6").
*: Any naval officer who thinks this is not possible any more on a destroyer should be fired immediately for being too stupid to serve.


  1. The demise of the large caliber naval gun has rather more to do with the ascendance of aviation, rockets and missiles.

  2. This wasn't about some "demise", and guns are still much more economical for naval fire support for ground forces and also much more lethal than missiles at short ranges, even out to the horizon.
    Eight Harpoon missiles can be interecepted or deceived, but no warship has a defence against or could withstand 60 dumb 155 mm shells without being mission-killed at least.

  3. I find it totally perplexing how the U.S. navy think its needs rail guns or other fancy shit to do NSGS. You don't need high tech for that mission, you just need a big gun and a fair sized hull (like the royal navys monitors of WW1 and WW2).

  4. Why would naval forces accept a 6 inch naval gun that is more or less from World War 1 era when modern 5 inch guns are automatic with much greater range and rates of fire? Even the modern 155mm SP artillery are fully automatic.

    Also, how are guns more lethal than missiles when missiles are generally more accurate with a larger warhead?

    1. A wide range of 155 shells with effects tailored to support or engage ground forces are available, while 127 mm does not offer this. 155 mm also offers more effect per shell and its sustained rate of fire would be quite the same if not much better than with 127 mm automatic.
      One would need to use new semi-fixed 127 mm cartridges and slow manual loading to mimic a howitzer's manipulation of trajectories and thus important optimisation of the descent angle of the shell.

      127 mm (5") is furthermore neither a good calibre against surface targets on land or at sea nor a good calibre for anti-air fires. 76 mm with 5x to 7x the rate of fire of the "lightweight" 127 mm guns from the USA (Italian ones have higher rpm, but are heavier) is much better for anti-air fires.

      This blog article thus took the issue of the old idea of having dedicated anti-surface and dedicated anti-air guns to show how unnecessarily sophisticated, expensive and/or fruitless attempts of naval bureaucracies were.

      On your second point; the answer was already given two days ago, feel free to simply read it.

    2. I don't see why those same shells can't be developed for a 5 inch gun. They may not be as powerful as a 155mm, but certainly better than army's 105mm and a much cheaper option.
      And the US Navy 5 inch gun has a rate of fire of 16-20 round per minute while Otobreda can reach 40 rounds per minute. I don't see how that is possible for a manual loading gun to match. And manual loading guns require much greater crew sizes when navies have been attempting to reduce the size of needed crews. And if you forgo a turret or shield, then they're also exposed to the elements and hostile fire.

      So you're saying 60 dumb shells is more lethal than 8 harpoon missiles because ships have no defense against them. But wouldn't those 60 dumb shells come at a much slower rate and be much easier to dodge on top of their inherent (relative) inaccuracy? That simply taking evasive action would give a gun a very hard target to hit.

    3. Manual laoding doesn't need to match such rates of fire. They're close to irrelevant for shelling ground targets. Those guns overheat badly after a few shots, and are down to the same sustained 2 rpm or so as howitzers real quick.

      A manual-loading gun doesn't need a single additional crewmember. That activity is so rarely needed that kitchen personnel could be employed if necessary.
      About the elements; submarine deck gun example, period. Counterfire; relevant only in ship/ship actions if ever. Bigger probelm is the ship would be exposed, shield or none.

      About 60 rds; a 30 kts warsip has a sustained speed at turns of only 15 kts only. You cannot dodge accurately-aimed shells for long like that.
      The 6" gun rate of fire is rather a point in favour of 5" automatic, which at least for the purpose of a firepower kill may be more effective out to 10 nm or so due to higher RoF. It's less capable of sinking, though.

      The general idea is that the price and size of anti-ship missiles limits their available quantity badly, while 6" shells are easily stored in the hundreds. Hard kill defences are thus easily attrited. Soft kill works not at all. So far medium range SAMs such as Sea Sparrow or ESSM Block 1 can be used instead, at least within illuminator radar line of sight. This ability will fade soon due to the even higher costs of new such SAMs (the ESSM Block 2, for exmaple).

  5. So that would make the gun only useful for shelling ground targets then. Why have that when current guns also have some use for surface warfare and AA work? And wouldn't naval guns be able to shoot for much longer due to thicker barrels? I believe there been a cases where WW2 surface ships would shoot most of their ammunition during combat.

    I'm not sure what counter point noting a submarine deck gun. They're usually submerged and firing torpedoes I thought. And the lack of shield/turret means that a single near hit can take out the gun and its crews as they're completely exposed to hostile fire and shrapnel.

    Considering it takes something like 30 seconds for the shells to arrive, wouldn't a small changes in course all that be needed to dodge naval gun shells?

    Soft kill doesn't work? What little I recall shows that ECM or soft kill have a much better record than hard kill methods do. And I believe in the case of the US Navy at least, carrier aircraft are primary users of harpoon missiles so they can use them in greater numbers and angles of attack that can overwhelm a defending ships defenses with the anti-ship mission being rather secondary for destroyers.

    1. NO, no, no - and I won't elaborate on this any more becuase your problem here is that you don't read carefullly. The answers were written already.

      For starters, I don't argue that warships should be equipped with semi-automated 155 mm guns. It was an example to show how naval bureaucracies weren't effective enough at pursuing something they actually wanted becuase they went for gold-plated solutions, unable to see how easily even primitive solutions could fit the bill.

    2. My apologies.

      If it is really an issue of the guns being "gold plated", what features are really gold plated though? Other than the 155mm AGS perhaps, what "gold plating" is there? The 8 inch you linked to navweaps explains it was only canceled due to budget cuts. The German 155mm is the gun and turret from the current German SP artillery.
      Having an automated gun in a turret can't be gold plating as that been around for many decades.
      And your own solution sounds like a "stone plating" 10% solution. It is like suggesting a WW1 biplane when an air force is struggling to produce a modern fighter.

    3. 8" MCLWG - about 80 tons
      AGWSTP - meant for a 180 km range
      155 mm VAGS - meant to fire guided projectiles vertically only
      155 mm AGS - in excess of 100 tons apparently

      By comparison, a manuallly loaded gun with automated gunlaying would be about 20 tons or less, and a bolt-on solution that requires no deck penetration other than for a few cables and screws.
      Even MONARC was deck-penetrating and heavier.

      I understand most examples of gold-plated programs were USN examples, but I avoid to openly bash them all the time because this leads to the unnecessary distraction of "anti-Americanism" charges.

  6. A very interesting piece.

    I think I'd go the other way though.

    A 155mm with a poorly trained crew (cooks) is going to provide negligible gun fire support and very limited ship to ship fire.
    A 57-130mm rapid firing cannon may do little structural damage to the hull of a ship (and provide no shore fire support), but they would be highly effective at clearing the decks, destroying box launchers, radar, guns, and the tower of other ships.

    The real world application of either seems to be a pretty unlikely course of events though.