The question of the upcoming deck-gun for the refurbished Hamina-class FAC was cleared up today, as BAE announced a deal for four Bofors 40 mm Mk. 4 to equip the vessels of the class. This is in line with the original reports, and means that the vessels will retain an amount of gun-fighting capability post-MLU, an especially important feature considering the small magazine sizes of both the heavy anti-ship missiles as well as the Umkhonto surface-to-air missiles.
I’ll admit that the headline above is slightly misleading, as while the words “40 mm” and “Bofors” certainly are a classic combo, the Mk. 4 share little except the calibre with the classic Bofors L/60 of WWII-fame. In between the two, the Rauma-class FAC and importantly the Kataanpää-class MCMV (poised to stay in service alongside the Hamina) are both equipped with the Bofors 40 mm Mk. 2. This is based on the L/70 long version which is more or less a completely new weapon using a longer round (40 x 364 mm vs 40 x 311 mm) when compared to the original L/60. The L/70 first entered service in 1948, but has proven to be a solid design which is found in a large number of single- and twin-mounts in navies throughout the world.
The new Mk. 4 turret still rely on the same L/70 weapon, but apart from looking like a ball (or rather something like a slightly distorted truncated hexagonal trapezohedron, but let’s stick to ball for now), the nice thing is that it is able to switch between different kinds of round on the fly (up to 100 rounds can be stored in a ready to fire mode). Further improving the flexibility its ability to use programmable 3P rounds, which allows e.g. for precise air burst or armour penetration capability from the same round, the exact mode being set the instant before the firing takes place. Finland is now the third country to acquire the Mk.4 after Sweden (a single patrol vessel that underwent MLU, since retired) and Brazil.
In the meantime, work on the first vessel to undergo MLU, FNS Tornio (’81’), started right away after the deal with Patria was announced, and already by the 16 January Finnish public broadcasting company YLE was able to show pictures from Western Shipyards in Teijo which showed that the earlier 57 mm gun and most sensors and antennas had been stripped from the vessel. Interestingly enough, the CEO of Western Shipyards states that they secured the contract in close competition with Uudenkaupungin Työvene and RMC, the shipyard which is set to build the new Pohjanmaa-class (Squadron 2020). While the work would without doubt have provided valuable experience to RMC, it might very well have been hard pressed to finnish all four vessels before the first Pohjanmaa start to require full focus.