Coast Guard Cutter Stratton fires its MK 110 during a gunnery exercise in the Bering Sea April 28, 2021. Routine training and live-fire exercises provide opportunities to evaluate and improve procedures, test capabilities and maintain proficiency. U.S. Coast Guard photo courtesy Ensign Molly Dolan.
Naval News reports BAE has delivered their 50th 57 Mk110 gun system for use on US warships. In this case, that gun will go to a US Coast Guard Cutter, almost certainly OPC #3 or #4. Significantly the first US Mk110 installation was on USCGC Bertholf, commissioned Coast Guard Day, 2008, three months before the first Littoral Combat Ship, USS Freedom (now already decommission).
Fifty guns is really not a lot compared to the number of Oto Melara 76mm or the 5″ Mk 45, but it is on a lot of ships, and the fact that it is expected to equip 20 new FFGs and 25 OPCs in addition to, still yet to be delivered NSCs and LCSs, seems to guarantee long term US Navy interest in the system. Current plans call for a total of 87 ships equipped with the Mk110, 51 Navy and 36 Coast Guard (excluding the first four LCS which are being decommissioned).
We are seeing that interest in development of the ALaMO and MAD-FIRES rounds.
I still think, because of the Coast Guard’s missions and the lack of alternative anti-surface weapons on cutters, that our large cutter should have 5″ Mk45 weapon systems (even if only recycled 5″/54s). After all, any improvements you could make to a 57mm round, you could also make to a 5″ (127mm) round, but it is encouraging to see new more capable and more accurate rounds being developed for the gun we do have.
Chuck Hill's CG Blog 
But how many did Bofors sell under SAK for ~35-years, before BAE’s acquisition of Bofors 1999…
They are still selling made in Sweden models. Have certainly sold more than 50, but has never been as successful the 76mm. I just think how many 5″/38s or Bofors 40s were made and 50 is almost ridiculously few.
SAK produced the 57mm Bofors for six other countries, not including their own (i.e. Yugoslavia, Mexico, Canada, Norway, Malaysia and Finland! The Leonardo/Oto Melara 76/62 also has maintenance issues if fired too long…
50 for the US market, but the 57mm, in all it versions, rivals the 76mm. Lots of navies and coast guards use it, the US being one of the later adopters of it. While it is certainly not perfect, and it packs a smaller punch per round than the 76mm, it has incredibly smart ammo and an impressive rate of fire plus low observability for the mount vs the 76mm. I’m surprised the RN didn’t select it over the 40mm or at least
But the 76/62 has a Cooling Issue with it’s Barrel! Though “Watercooled” the barrel will heat up to the point that when after 70-rounds are fired in rapid succession, the gun will jam. Which then requires someone actually physically unjamming whatever round type is stuck within the breech. Also the Super Rapid won’t fire the older Rapid ammunition, because Oto Melara did a design change on the ammunition for the SR gun system, which isn’t compatible with the older Rapid model. Much like the .308 Win vs. 7.62×51 Nato quandary…
For anyone curious there is a history of the 57mm and information on its characteristics, applications, and operation here: http://navweaps.com/Weapons/WNSweden_57-70_mk123.php
@DaSaint, RN did select the 57mm for the Type 31 frigate. Each will have one 57mm Mk3 and two 40mm Mk4.
Regarding the Oto Melara, “One of the most popular naval guns ever produced, with OTO-Melara reporting that about 1,000 Compact and SR guns were in service in 51 navies around the world as of December 2002. This weapon is produced under license in Australia, India, Japan, Spain and USA. It is manufactured in the United States by United Defense (now part of BAE Systems), in Japan by Japan Steel Works and in Spain by FABA (formerly IZAR, formerly Bazán).”
They have built a bunch more since then so really the number of 57mm guns out there is not even close.