Coast Guard Cutter Stratton fires its MK 110 during a gunnery exercise in the Bering Sea April 28, 2021. U.S. Coast Guard photo courtesy Ensign Molly Dolan.
The Royal Navy has chosen the BAE Bofors 57mm Mk3 to arm a new class, the Mk31 general purpose Frigates. This is the same gun that arms National Security Cutters (NSCs) and Littoral Combat Ships (LCSs) and which will arm the Offshore Patrol Cutters (OPCs) and the new Constellation class guided missile frigates.
UK based Navy Lookout has published an independent evaluation of the weapon and its ammunition. This is almost two years old, but it is well done. It makes some good points discussing the both the advantages and limitations of the weapon. I would point out that they note, “The days of medium calibre guns being used against other ships are long gone…” It is adequate for signaling by firing across the bow and for engaging small craft, but maybe we might want to think about adding a weapon suitable for use against ships since that should be part of even our peacetime skill set.
Unfortunately, their hopes for the “Multi- Azimuth Defense Fast Intercept Round Engagement System” (MAD-FIRES) guided round will not be realized. It seems the MAD-FIRES round was a non-starter. I checked both the Raytheon/RTX and the DARPA websites and neither had any mention of MAD-FIRES. I thought perhaps the MAD-FIRES program had failed when Northop Grumman was awarded a contract to develop a maneuvering 57mm round, but even in that case, it was intended for use against “fast moving surface threats, drones and swarming threats” not cruise missiles as was the case for MAD-FIRES.
Chuck Hill's CG Blog 
T31 will go to sea without ASW equipment. It isn’t so much ‘general purpose’ as ‘lieutenant purpose’!
The Royal Navy deciding to clasify T23 without 2087 as ‘general purpose’ is coming back to haunt them.
T26 will be very quiet and very well equipped in terms of ASW. But with T45 lacklustre MOAS based sonar no longer manned and T31 having no such equipment ASW is going to be a problem for the RN.
Saying all that T26 will be the only variant of the Global Combat Ship not able to fire an area AA missile. That is something I think all variants of FREMM upon which the USN Constellation class can do. And of course the latter is an AEGIS ship too.
Not good. From the world’s second best navy to a curate’s egg third rate oddity
The Type 31 is starting to look like a very large Coast Guard cutter.
Maybe we can come up with a containerized towed array that could be used on ships with no organic ASW sensors.
Many of here say it will be deployed to the backwaters and doesn’t need a sonar.
There aren’t many backwaters these days and I am none to sure why a backwater would need the presence of a RN warship.
My opinion is that there are places where there is little threat of enemy surface ships, and some places where the air threat is minor or non-existent, but there are no ocean waters where we can be sure there are no submarines. I see that to be the case over about 2/3s of the Pacific.
Yes, submarines can launch missiles, but they will not carry many. They are most likely to use the few they have against targets on land. They are extremely unlikely to use them against escort vessels. So ASW escort vessels with only minimal AAW and perhaps no ASCMs may still be very useful.
In the meantime, the US Navy is still pursuing a guided, hyper-velocity 5-inch projectile.
If this round works as intended, the 5-inch gun could turn out to be the better gun for the Coast Guard.
It would have much greater range and lethality than the 57mm against both air and surface targets. It would give the larger Cutters better anti-air and anti-surface capability without the costs and complications associated with missiles.
Navy placed contract with NG Oct ’23, will be of interest if anything comes of it and whether it meets its claims and is affordable.
This NG contract leads one to believe there are issues with the 57mm ALAMO round, either in performance, cost or both.
I talked about the Northop Grumman guided round here.
“Northrop Grumman to Develop New Guided Ammunition for the US Navy” (57mm) –News Release | Chuck Hill’s CG Blog (chuckhillscgblog.net)
But this is not expected to be effective against cruise missiles as the MAD-FIRES was supposed to have been, and its development does suggest that the ALaMO round was not entirely successful.
I have always felt not putting the 5″ Mk45 on cutters was a serious mistake, from 2012.
Case for the Five Inch Gun | Chuck Hill’s CG Blog (chuckhillscgblog.net)
Any improvements that can be incorporated into a 57mm or 76mm gun can be included in 5″ projectile. The greater destructive volume of the 5″ can compensate for slight inaccuracies. The greater range means if you use the same technology, the 5″ will always have a greater reach meaning if threats are arriving simultaneously the 5″ will have more opportunities to engage.
There were lots of spare 5″/54 Mk45s available from scrapped USN ships that could have been used to arm cutters, but we seem to have missed that opportunity.
I remember your post about the 5″ gun. At that time, the 5″ gun might have been seen to be overkill.
What we are witnessing now in the Red Sea and the Black Sea, is evidence that the world has changed. Threats have changed.
Any ship can be held ask risk by cheap airborne and seaborne drones.
The Navy is learning a lot in the Red Sea. If anything, the 5″ gun is making a come back.
Cost per shot and magazine depth have taken on more importance.
Due to these things, there is renewed interest in longer ranged, guided projectiles for the gun.
I would not be surprised if a Flight II version of the Navy’s Constellation Class FFGs, went back to the 5 inch gun.
The intent with the 5″ for the Cutters would not be to turn them into 1st line combatants, but to help them survive and be more effective in roles they are already tasked with.