Alternatives to the 76mm Oto for the USN

[uk 75]

One of the surprising things that happened in the 70s was that the USN decided to buy an Italian gun for its new Perry class frigates.

MK 75 76mm/3-inch gun

I have looked without success to find what other weapons were looked at before the USN made this choice.

 

[Colonial-Marine]

Unless they wanted to resurrect their own 3"/70 last used in the Mark 37 mounting or the UK's counterpart 3"/70 Mark 6 I don't think there was any other choice in the 76mm/75mm caliber. The only other real alternative besides for those would have been the Bofors 57mm which fires a lighter shell although at a faster rate of fire.

Could they have gone with a larger caliber? Probably not in that same spot on the OHPs.

 

[isayyo2]

Maybe excess 3"/50 twins or 5"/38 pulled off recently decommissioned ships like FRAM destroyers or other vessels in mothball?

 

[TomS]

One of the surprising things that happened in the 70s was that the USN decided to buy an Italian gun for its new Perry class frigates.

MK 75 76mm/3-inch gun

I have looked without success to find what other weapons were looked at before the USN made this choice.

Early proposals for the PF-109 (which became the FFG-7) had an OTO-Melara twin 35mm gun instead.

The process that (eventually) led to the 76mm being adopted started as a study of self-defense for a notional PF variant without SM-1 -- options were Sea Sparrow, a 5-inch/54, the 76mm and twin 35mm OTO-Melara guns, or Phalanx. But fairly early on, that variant was dropped and the best solution was judged to be SM-1MR plus the twin 35mm. And that version shows up in the early PF sketches. Somewhere along the route from PF to FFG, they added Phalanx as well and probably decided to adopt the 76mm instead of the twin 35mm since it at least offered some anti-surface capacity and was almost as good in AAW.

 

[DanielStarseer]

Could the decision to go with the 76/62 on Perry class frigates, partially been inspired by US interest in Italy's Sparviero (sp?) attack hydrofoils and eventual creation of the (6?) USN Pegasus-class missile hydrofoils, on grounds of commonality (there's that word) ?
Seems no other USN ships took any interest.

 

[timmymagic]

Seems no other USN ships took any interest.

Was it tied in with the USCG purchase of OTO 76's as well?

I lean towards there being no other choice, remember the RN had them on the Hong Kong based Peacock Class.

 

[TomS]

Could the decision to go with the 76/62 on Perry class frigates, partially been inspired by US interest in Italy's Sparviero (sp?) attack hydrofoils and eventual creation of the (6?) USN Pegasus-class missile hydrofoils, on grounds of commonality (there's that word) ?
Seems no other USN ships took any interest.

This is possible. The FFGs and PHMs were basically running in parallel, and the Mk 92 fire control system and 76mm gun were tested for both at the same time.

Was it tied in with the USCG purchase of OTO 76's as well?

The other way around. The 270-footers (the Bear class) were designed a couple of years after the FFG-7s, and I believe the Navy paid for the weapon systems on the cutters, so they got whatever gun the Navy adopted.

 

[apparition13]

Could the decision to go with the 76/62 on Perry class frigates, partially been inspired by US interest in Italy's Sparviero (sp?) attack hydrofoils and eventual creation of the (6?) USN Pegasus-class missile hydrofoils, on grounds of commonality (there's that word) ?
Seems no other USN ships took any interest.

Someone just mentioned in the Burke thread that they were considered for those.

 

[iverson]

Unless they wanted to resurrect their own 3"/70 last used in the Mark 37 mounting or the UK's counterpart 3"/70 Mark 6 I don't think there was any other choice in the 76mm/75mm caliber. The only other real alternative besides for those would have been the Bofors 57mm which fires a lighter shell although at a faster rate of fire.

Could they have gone with a larger caliber? Probably not in that same spot on the OHPs.

I think I recall that the 57-mm Bofors was considered but rejected because its shell was considered inadequate for surface-to-surface fire.

 

[TomS]

I think I recall that the 57-mm Bofors was considered but rejected because its shell was considered inadequate for surface-to-surface fire.

The only mention I can find of the USN evaluating the Bofors 57mm (before LCS) is a note in Friedman's World Naval Weapons that the USN Foreign Ordnance Review Team considered it heavy compared to the OTO-Melara 76mm and 35mm twin. The inclusion of the 35mm suggests this was in the context of the FFG-7 and PHM armament evaluations, since that was the last time the US seriously looked at the twin 35mm.

This is an odd conclusion, IMO: the Bofors 57mm Mk2 weights ~6.5 tons without ammo, compared to ~7.4 tons for the OTO-Melara 76mm Compact (also without ammo). So yes, in theory it's a bit heavy compared to its caliber, but not once you consider the higher RoF and throw weight of the 57mm. Operationally, they're both very similar. This feels like a reverse justification for a decision already made.

The fact that Italy was a NATO member and partner on PHM was also certainly a factor.

Could the decision to go with the 76/62 on Perry class frigates, partially been inspired by US interest in Italy's Sparviero (sp?) attack hydrofoils

Revisiting this, Freidman confirms that the PHMs nearly got the 35mm as well. I presume that the USN had decided that the two designs would have the same gun, whichever one was adopted. And when the time came to make the final decision, there were concerns about the 35mm (limited burst capacity, inadequate ASuW capacity, reliability issues) so the 76mm won more or less by default.