Naval History Forums

This is a question that has come up before, inevitably featuring weapons developed in 1944/45.

But what were these best weapons on each side say up to 1942?

The best heavy DP gun was the US 5in/38.
The best large automatic cannon was the 40mm Bofors.
The best light automatic cannon was the 20mm Oerlikon.

Tiornu wrote:The best heavy DP gun was the US 5in/38.
The best large automatic cannon was the 40mm Bofors.
The best light automatic cannon was the 20mm Oerlikon.

One thing that made them more effective was good fire control. A lot of people ignore that. They were all good guns, but by the end of the war even the 20mm had a lead computing sight.

Hi RF.

The best DP gun that we British had was the 4.5 inch dual mounts (Renown, Queen Elizabeth and Valiant).

The 2 pdr POM-POM jammed alot in the early years.
All concerned were pleased to have the 40mm BOFORS instead

The pompom was a great weapon when first introduced, but getting old by 1939.

One lesson learned from war experience, was that the AA issue was not so much to do with numbers of weapons, as it was fire control. Sixteen director-controlled weapons (all other things being equal) were more effective than 32, without directors. I believe this held greater merit among medium- to large-bore guns, than to light cannon and machine guns. Obviously, a director-controlled 50-cal. MG would be satirical....

In fact, the effectiveness of an AA gun system depends on four factors:

1. The balistics of the gun itself
2. The loading arrangements
3. The mount (basically how fast and how accurately the gun can turn and be elevated)
4. The fire control

All in all, the USN had the most effective AA gun systems in the heavy (5in) and medium (Bofors 40mm) sizes but I do believe the only light AA worth of anything else than psychological effect was the German 20mm Flakvierling quad mount.

By the war end, however, there was a general understanding that heavier shells were required. Most countries followed the path of the Germans with their 55mm and 30mm AA guns that were under development.

Regards

Rafael

Hello to all ¡¡
I would tend to prefer the Mauser 20 mm C38, specially in the "Vierling" mounting over the "Oerlikon", because It had better ballistics and a very similar rate of fire (per barrel), IMHO. Overall, the Optics of the "Vierling" were excellent and It made the most powerful and devastating short range AA mounting of the war.
Best regards

I would say the 5"/38cal was a good AA gun, paired with that magical shell.

for pre-war AA weapon... the 5"/25cal looks to be a pretty capable AA weapon, and not half-bad dual-purpose gun, at likely battle ranges.

Any opinions on the USN's 5"/25cal?

yellowtail3 wrote:I would say the 5"/38cal was a good AA gun, paired with that magical shell.

for pre-war AA weapon... the 5"/25cal looks to be a pretty capable AA weapon, and not half-bad dual-purpose gun, at likely battle ranges.

Any opinions on the USN's 5"/25cal?

Ballistics and mounts weren't nearly as good as the 5"/38, so they were mediocre. The poor ballistics made them of marginal use at long range against ships, but they made good submarine deck guns, and by the end of the war most US submarines had one or two of these weapons taken from the old battleships for use against ships not worth a torpedo.

Edit: Note that older US battleships had 5"/51 cal guns as a secondary battery, although the 5"/25 was also used in the surface role.

40mm Bofors with a proximity fused shells, thats my vote

Late war statistical analyses of USN AAA capability against the Kamikaze threat credited the director-controlled 40mm (keeping in mind that these were almost exclusively in twin or quad mounts) with 50 pct of kills.

The director-controlled 5/38 with VT-fuzed ammunition was responsible for about 25 pct.

The 20mm guns with 25 pct of kills. Although the 20mm was criticized in some respects for its inability to physically destroy an oncoming target or prevent launch of its ordnance, it did have important advantages over other AAA weapons on board USN ships: (a) being a manually operated weapon, it would remain fully operable even in the event of a total loss of ship's power; (b) being a light, compact and self-contained weapon system, it could be installed in almost any location on a ship where deck space was available. Late war improvements (twinned gun mounts and Mk14 gyro gunsight) promised further improvement in effectiveness.

An often overlooked factor (when examining USN AAA at any rate) was the late war development of much improved AAA director control systems, which could as much as double the effectiveness of the AAA defense.


Byron

40mm Bofors with a proximity fused shells, thats my vote

A proximity fuze for 40mm was not available during the war and would have been of dubious value in any case since the effectiveness of proximity or any air bust shell is determined by the weight of explosives for blast effect plus the amount of steel in the shell which would determine the splinter effect. A ~2-lbs 4cm shell would have only about 2-oz of explosive. When one sees a film in which 40mm rounds are detonating in the air, what is actually happening is the shells are self destructing at the end of tracer burn.

The fact is that medium calibre DP guns were not very effective in downing aircraft. The USN 5"/38 probably got more than any other similar gun, but it's kill rate was highly inflated. One of the problems with trying to get a handle on the actual kill rate, is that, by definition the 5"/38 was being used as an area weapon, with many ships with the same gun size engaging the same targets. Over claiming was the inevitable result. Overall the 5"/38 probably downed about 1 aircraft per 2000 rds of MT fuzed ammo, and I would suspect that this kill rate was typical for all similar sized weapons in WW2.

dunmunro wrote:The fact is that medium calibre DP guns were not very effective in downing aircraft. The USN 5"/38 probably got more than any other similar gun, but it's kill rate was highly inflated. One of the problems with trying to get a handle on the actual kill rate, is that, by definition the 5"/38 was being used as an area weapon, with many ships with the same gun size engaging the same targets. Over claiming was the inevitable result. Overall the 5"/38 probably downed about 1 aircraft per 2000 rds of MT fuzed ammo, and I would suspect that this kill rate was typical for all similar sized weapons in WW2.

..... For what it's worth, the rounds per bird figures for 5-inch AAA in the afore-mentioned report as follows -


KAMIKAZE ATTACK
------------5in Com-----5in VT
Oct 44-----1479---------242
Nov 44-----1213--------324
Dec 44------493---------218
Jan 45-----2675---------402

Average---1162---------310

- - -

CONVENTIONAL ATTACK
------------5in Com-----5in VT
Oct 44-------748---------65
Nov 44-----2601--------798
Dec 44------795---------179
Jan 45-----1765-------1083

Average----960---------624



Byron