January 07, 2020
A trend in recent years has people investing a lot of time and energy into learning and attempting to master shooting at very long-range. I know several people who compete in the King of the 2 Mile circuit. One of their most important aspects to consider is the choice of barrel for the rifle and the caliber. Many people incorrectly assume that technology has transformed the manufacturing process, and nothing in the past could do as well, or last as long as they do today. That is not at all correct, albeit this will not be an apples to apples example. One might think that 6mm or .30-caliber barrels have the best track record for accuracy and longevity but it’s easy to imagine the response when someone would say 381mm instead. That’s not a typo that snuck past the editor, indeed 381mm (15-inch) barrels mounted on combat vessels have one of the most stellar records of accuracy and longevity in the history of projectile firearms.
Now getting more specific, it’s the Royal Naval Ordnance BL 15/42 Mark 1 that’s our focus as their French and German counterparts simply lack the supporting data. So let’s travel back in time to the height of Britannia’s Naval power over a century ago. It’s only been six years since the launch of HMS Dreadnought initiated the first international arms race. Any nation with money or ability was building these ships as fast as possible. Shipyards in the United Kingdom were filling orders for ever more powerful designs to foreign countries like Japan, who were likely threats. The Admiralty had to plan a response, one that would challenge not only foreign powers but their own industry. This plan would raise the stakes and create what would be called by later historians as Super-Dreadnoughts. While there is no uniform definition and such, these ships shared most of the following characteristics. They were to reach speeds of 24 knots or more, carry all centerline main batteries of 14-inch guns or larger, and heavier armor than any previous dreadnought. Now we won’t really get into the aspect of the battlecruiser concept as that’s a whole different discussion. The first ships to have this banner in the Royal Navy were the Queen Elizabeth (QE) class battleships which were being launched at the dawn of World War One. One of their key features was a new 381mm/15-inch gun. This gun would be mounted on all capital ship for the remainder of the war, and all but two classes of ships until the end of the battleship era.
Now what makes the history of these guns more unusual is that there was no single arsenal producing these giant rifle barrels. In fact seven different companies built 186 production barrels between 1914 and 1918. So these guns were 381mm bore diameter for a true 15-inches, the designation BL 15/42 means barrel of 15-inch bore, 42 calibers in length. The use of calibers was an old designation system. To reach this number the length of the barrel was divided by the diameter of the bore. So in this case reversing the calculation means the barrel was of 630-inches in length, or 52.5 feet before adding the breech. This added another 20 inches to the overall length. These barrels had 76 grooves with a right-hand twist of 1 turn in 360 inches if you want to compare them with their much smaller cousins.
The BL 15/42 used a fairly unique breech block (bolt face), the Whelin, to contain the explosion within. The Whelin could reach 75% locking engagement in just a quarter turn; now that’s a short throw! When these barrels were finished they tipped the scales at 100 tons each! They were the heaviest rifled cannon of the period. Now, during this time all heavy naval artillery barrels were constructed using multiple sleeves in order to achieve the desired results. What makes the BL 15/42 unique among its peers is that instead of using a design where the outer sleeves were shorter, giving a stepped look, or an encased tapered finish like the ones on US battleships, these were all the same length giving a bull barrel look. This also allowed for each sleeve to be forged in different ways for a specific purpose. It created a very rigid design, much like many of the match barrels we see today. Another ingenious advantage of this was that it allowed for the inner-most sleeve to be replaced when the rifling was worn down and accuracy degraded. So, whenever a ship came in for refits, the old barrels would be removed and sent to be refurbished. Then a set of previously refurbished barrels were taken from storage and mounted in their place. Barrels thus traveled to various ship within the fleet. Sadly it is hard to find any record kept of the travels of these 186 guns from 1914 to 1959. Any match shooter would like to have a set of barrels last for 45 years!
Originally these guns propelled shells weighing from 1,910 pounds (APC Mk1a) to 1,965 pounds (HE 8crh) at a muzzle velocity of approximately 2,465 fps. The maximum elevation was 20 degrees giving them a range limit of 23,700 yards. During the interwar period all of the different shell types were made to a uniform 1,938 pounds in weight while velocity remained unchanged. Meanwhile the turrets were modified for a new elevation of 30 degrees increasing range to 29,000 yards. Barrels had to be refinished on an average of 335 rounds fired.
During their service these barrels were used in conflicts all around the globe. They first saw action at Gallipoli. Then the massive naval action at the Battle of Jutland until their last shots fired in support of troops during the Korean War. At Jutland their initial salvos were fired at 19,500 yards, safe from German return fire. They scored hits at a range of 19,000 yards (over 10 miles!) setting a new record. Every naval campaign the Royal Navy was involved in had ships with BL15/42 guns participating in some form. It was the careful ruse using the “intercepting” battlecruiser HMS Renown and her 15-inch guns which caused Hitler to give the order for the KMS Graf Spee to be scuttled rather than sunk in action. The Battle of the Atlantic is filled with accounts of these guns being used in action against enemy ships and for shore bombardments. In the Battle of Denmark Strait HMS Hood open fired on KMS Bismarck at 26,500 yards (over 15 miles), one of the longest naval battles of the war. In the Mediterranean, HMS Warspite made history by recording the longest hit against a moving target by a battleship when it connected with the Italian battleship Guilio Cesare at a range of 26,000 yards or 14.8 miles (!) during the Battle of Calabria. No other model of naval gun in the history of the Royal Navy earned as many battle honors. From the QE class in 1914 to HMS Vanguard, England’s last battleship, the BL 15/42 did everything that was asked of it.
After World War II the economies of the global powers were on shaky grounds. Complicating the situation was the start of the atomic age where tests proved whole naval battlegroups could be wiped out with a single nuclear blast. So, in short order all nations either retired or scrapped their remaining battleships. Years later, as the US was reactivating its Iowa class battleships Britain went through the Falklands War in 1982. In the resulting analysis of the conflict several came to the position that had HMS Vanguard been available the casualties and material losses would have been greatly reduced. To paraphrase a fictional admiral the “Argentinians could not repel firepower of that magnitude”. If one were to look for any remaining BL 15/42s the last pair guards the entrance to the Imperial War Museum in London. There actually may be a time when once again big gun ships return to the navies of the world. As the cost of missiles spirals higher and countermeasures increase in effectiveness, navies are revisiting the advantages of naval artillery. This is due to a very simple principle, once the projectile leaves the barrel there is no force on earth to stop it.