40 mm Bofors AA guns made in GB and US

[Bill Murray]

Stellan:

I paid 10 pounds (ca. $18 US at a local bookseller) for that book when it was printed. I do not think it is worth the price you were quoted, especially if you can obtain it from one or more libraries.
It is a good book but not an exhaustive history and quite a lot of what you have posted here is the same stuff found in the book.
I would say a fair price would be $50 or equal in Kronor if you can find it for that. It is worth that much anyway.
Bill

[Stellan Bojerud (RIP)]

Thank You!

1. Bill for information on Terry Ganders book. Very helpful. I will follow your advice.

2. John for the pictures of Crusader III and F60B. Quite interesting.

3. Here is something for Rob:

Your Bofors gun is probably Hungarian made.

38U. U = Unkarilainen = Hungarian.

The Hungarian State Railway Factory was a sub-contractor to Bofors which placed orders there.

The factory was Mágyar Allami Vaggon és Gépgvár (MAVAG)

From Hungary the guns were sent to Sweden and sold from there.

Hungarian made guns had the M 34/38 Johasz-Gamma Loelemkepzo sights - usually only called Gamma.

Rob, does your gun come with the 4-wheel carriage with two folded box-type outriggers?

If a gun is made in Bofors Sweden this mark should be found on the breech:

[Tony Smith]

I'd known that this was a Canadian gun, but now thanks to Stellan I also know that O.F.E/C. means Otis Fensom. Gun No L8031:

[Stellan Bojerud (RIP)]

Thank You Tony!

You are adding a piece to my puzzle. Your gun is 8031/1942 and the one I mentioned is 28318/1943. The difference in numbers are more than 20000.

I hope other gun-owners will submit some more numbers.

A question: Does your gun have the short wheelbase Mk I carriage with box-shaped outriggers or MK 2 long wheelbase Mk II with round outriggers?

And what type of sights? Small pre 1943 "spider-web" or large Mk IV 1944 "Stiffkey-Stick" demanding a sights operatior in addition to the two gunlayers?

[Hanno Spoelstra]

Originally posted by Bill Murray
I would say a fair price would be $50 or equal in Kronor if you can find it for that. It is worth that much anyway.

I don't have much to add to this thread, other than a quick search on abebooks.com shows Terry Gander's Bofors books commands high prices on the second hand market.

I vividly remember "playing" with a Bofors 40 L/70 as a small boy during one of the Royal Netherlands Army's annual open days. Great stuff!

H.

[Bill Murray]

Stellan:

You can have my copy. Send me a pm with your postal address and I will get it off when I return from our annual Hobby Exposition in a week or so. $95 to $100 is ridiculous.

You will get far more use out of it than I ever will. On your side, may I charge you with continuing to find and post somewhere more of the marvelous Dutch and Belgian softskins you seem to be finding goodness knows where. They are a most valuable contribution to the group, well me especially as they are mostly American makes, and are as rare as uncirculated coins.

And, for the record, I have not taken my daily pill yet so my mind is as sharp as a new tack for the moment.

Only 8 hours to go till tea time.


Bill

[Tony Smith]

The Gun has a long wheelbase "Platforms, 40MM., A.A., Mountings, Mark II" with the welded frame, round outriggers and 9.00-13 tyres. Mark I rivetted platforms are very unusual here, I've never actually seen one.

[Stellan Bojerud (RIP)]

1. Thank You very much Bill for Your kind offer regarding Terry Ganders book.

2. Thank You Tony. Yes, I thought the gun should have the MK II carriage.

40 mm BOFORS MK I - CARRIAGE MK I

The British MK I guns seems all to have been imported. They were made by:

Belgium (Fabrique Nationale,FN)
Hungary (Mágyar Allami Vaggon és Gépgvár, MAVAG)
Poland (State factories Starachowice and Poznan)
Sweden (Bofors)

Hungary and Poland aquiured license rights in 1935, Belgium in 1936.

The first British order for 100 guns was placed in Bofors May 1937. This was followed in 1938 by three orders for totally 230 guns and in 1939 another 179 guns.

This makes totally 509 guns of which 24 were placed under embargo by the Swedish Government in Dec 1936 - Jan 1940.

But all these guns could not have been made by Bofors as we can see from this:

1935 Ordered 76 - Delivered 0
1936 Ordered 92 - Delivered 12
1937 Ordered 195 - Delivered 48
1938 Ordered 468 - Delivered 62
1939 Ordered 385 - Delivered 118
1940 - Delivered 84

So obviously guns ordered in Bofors were also made in Belgium, Hungary and Poland.

I know that 406 guns were made in Poland of which 168 were exported to Great Britain, Netherlands and Rumania, but I do not know how many guns to each nation.

The model bought by Great Britain was M/1936 P (E). P for Poland and E for England. Also guns made by Bofors in Sweden were designed so. In Great Britain these were known as Mk I.

The Mk I guns had the "Bofors Course and Speed Corrector" with optical sights. The corrector was capable to calculate a target speed up to 563 km/h. In GB these were called "Polish sights".

In 1937 Great Britain aquired license rights and started production at Nuffield Mechanisation in Coventry.

The first gun delivered in summer 1939. These had simpler cross-wire sights, the "Forward Area Sighting System".

In 1943 the "Cartwheel Foresight" was introduced. This had three aiming rings for respectively 100 - 200 - 300 mph (161 - 322 - 483 km/h).

In 1944 the MK IV "Stiffkey-Stick" was introduced.

I am not sure which sights were the MK I - MK III.

The later British mass-production was MK III on the long wheelbase MK II welded carriage.

The MK II gun I know nothing about.

So to conclude:

Guns
MK I - Belgian, Hungarian, Polish and Swedish made
MK II - ?
MK III - GB mass-production (Can MK 1, US M 1)

The air-transport type (MK ?) had double-baffle muzzle brake instead of conical flame hider.

Carriages
MK I - Swedish type
MK I A - Polish type
MK II - GB welded long wheelbase (Can MK II)
MK III - ?
MK IV - Air-transport carriage
MK V - Morris truck (1944)

US M 2 was a welded version of the Swedish type with short wheelbase.

Sights
MK I - 1937 Polish?
MK II - 1939 Cross-wire?
MK III - 1943 Three aiming rings?
MK IV - 1944 Stiffkey-Stick (for sure)

So here is the MK I gun:

[Stellan Bojerud (RIP)]

Here is one for John:

The Polish text is: "Czlog p-lot Crusader AA". Czlog = Tank, p-lot = AA.

But the turret is not like those on Your pictures and the gun seems to be smaller than a Bofors.

And why is a Polish Tank serving with the British painted with the US white star?

[Stellan Bojerud (RIP)]

The "Kerrison Predictor" demonstrated in France March 1940. Standing extreme right: Col Kerrison (UK). The gun is of the early British type (Nuffield 1939).

Electro-hydraulic power-control units (known as "oil gears") were mounted on the gun carriage and linked by an electrical data transmission system to the mechanical director (box right) wich computed the firing data as it tracked the target.

The "Kerrison Predictor" was considered superior to all other AA fire control systems and also adopted by the US.

Who knows more about this equipment?

[Stellan Bojerud (RIP)]

Originally posted by Gunner


A few years ago Bofors produced a history book on the 40mm. I have a copy and will post the ISBN so that other enthusiasts of the mark can try to track down a copy.

Is this the book You were thinking of, Mike?

The photo: 40 mm water-cooled twin Bofors. USS Casco APV-12 off Attu Island July 1943. Note the USN sights type.

[John McGillivray]

Stellan,

The AA tank you are showing is British.

It is a Crusader III, AA Mk. II or Mk. III. It is fitted with twin 20mm Oerlikon AA cannon. The difference between the Mk. II and the Mk. III is only in the position of the radio. These AA tanks were used to equip the Anti-Aircraft troops in British, Canadian and Polish Armoured Regiments. The photo below shows a Crusader III AA Tank of the 1st Polish Armoured Regiment, 1st Polish Armoured Division in Normandy on 25 July 1944.

The 1st Polish Armoured Division was organized and equipped like a British Armoured Division.

The white “American Star” was adapted as the standard Allied Air Recognition Symbol and was seen on British, Canadian, Polish and US vehicles from early 1944 onwards.

John

[Gunner]

Hi Stellan:

Just to add to the confusion, Canada took the twin 20mm Oerlikon mounts made in Regina, Saskatchewan and modified them to mount single 40mm Bofors. The resulting hydraulic powered unit was called the "Bofin" or "Boffin" depending on who spelled it. It successfully served on HM Canadian Ships and as ground based airfiled air defences in Lahr and Baden-Baden, West Germany for many years. The army replaced them with the twin 35mm Oerlikon and the navy has put them back into service on our new fleet of minesweepers. Not bad for a gun made in 1942 (ish)! 62 years old and still going strong. To the best of my knowledge they are the oldest guns still in "frontline" service in the Canadian Forces.

The Ack-Ack tank drawing you posted is a twin 20mm version not a 40mm.

The Kerrison Predictor was a maze of gears and spinning bits that today is replaced by a small computer. For its time it was the cat's meow and remarkably improved the single shot kill probability of the 40mm. (SSKP is the statistical way we Bird Gunners calculate a gun's efficiency). I would dearly love to acquire a Kerrison Predictor to display with our 40mm. (see www.calnan.com/swords for some photos of our gun at various exhibitions and parades). I have an original fitted tarpaulin for a Predictor... now I just need something to put under it!

We should see if Geoff will start a new category for artillery and let this rapidly growing thread become its first. :idea:

I will post all the various numbers for our two guns (the Bofors and the M1939)... perhaps you want to start a register.

I will also dig out what I can from my library on Canadian production so you can add it to the knowledge base... just bear with me as my library is currently housing all the furniture and boxes from my basement while I drywall and finish my new basement office and den!:

Cheers! Mike

[Gunner]

John: Nice summary, great photo. BTW how do you do the arty tac sign in your profile?

Cheers! Mike

[John McGillivray]

Hello Mike,

Somewhere in this tread there are instructions as to how to set up the “AVATAR”.

http://www.mapleleafup.org/forums/sh...&threadid=2336

I was a Sgt in 2Fd Regt. RCA about 30 odd years ago. That is why I am using the AoS with the number 43.

While on my Arty Tech Course back in 1974, in Valcartier, I received a whole one days training on the 40mm Bofors on the Naval mounts. The guns belonged to 5RALC.

John

[Gunner]

Thanks John, the one I want to use is 2.22 k so I will have to get another version of it under 2 k. Too bad you couldn't get your boy to breathe cordite fumes! Cheers! Mike

[Rob Fast]

Yes Stellan, my carriage I believe is a Mk1 with square folding box outriggers. The breech cover also has the Swedish B-> stamp as you describe. The rims are 8.25 R 16, and look a little too modern for the rest of the gun, it would be nice to find the original spoked type rim. There are pics of my Bofors up on another thread entitled,"Have Bofors will Travel" , if you would like to have a look. Thanks guys, great info! Cheers Rob

[Gunner]

Hi Rob: Where is that string... I'm still learning how to navigate around the forum. Cheers! Mike

[Rob Fast]

and punch up Bofors. Page 3

[Gunner]

Thanks Rob: Learned something new tonight about surfing this forum. I note you were asking how to remove the barrel. Are you still looking for that info? Cheers, Mike

[John McGillivray]

The photo that I posted of the Polish Crusader III, AA is a Mk.III. You can tell this by the Radio Antenna mounted on the front hull. In the Mk. II the radio was located in the turret, while in the Mk. III the radio was installed in the hull front, next to the driver.

[Stellan Bojerud (RIP)]

Originally posted by Rob Fast
Yes Stellan, my carriage I believe is a Mk1 with square folding box outriggers. The breech cover also has the Swedish B-> stamp as you describe. The rims are 8.25 R 16, and look a little too modern for the rest of the gun, it would be nice to find the original spoked type rim. There are pics of my Bofors up on another thread entitled,"Have Bofors will Travel" , if you would like to have a look. Thanks guys, great info! Cheers Rob

Good morning Rob!
(at least morning for me, 07:14 Stockholm time)

I had a look at your gun. Seems to be in very good shape. I do agree - the wheels seems to have ben changed during the guns career with Suomen Puolustusvoimat

Here is a MK I carriage. Imperial War Museum.

[Stellan Bojerud (RIP)]

Slowly the puzzle gets more and more complete.

Otis Elelevator Co and Fensome Elevator Co amalgamated in 1905. In 1940 the Government built a gun factory at Otis Fensom Elevator Co establishments in Hamilton, Ontario. Some 3.000 workers were employed.

The first gun was delivered in August 1941.

In 1946 the gun factory was bought by Studebaker. In 1969 bought back by Otis and used as a warehouse. Closed 1987.

Here a 40 mm Bofors on MK II carriage training before D-Day.

I think someone could identify the unit by blue-red sign with white 73.

[Stellan Bojerud (RIP)]

Originally posted by Gunner


The Kerrison Predictor was a maze of gears and spinning bits that today is replaced by a small computer. For its time it was the cat's meow and remarkably improved the single shot kill probability of the 40mm. (SSKP is the statistical way we Bird Gunners calculate a gun's efficiency). I would dearly love to acquire a Kerrison Predictor to display with our 40mm.

I am sorry that I dont have one to give you. Only this pic of a Kerrison Predictor. US 211th AA Bn Leyte Oct 27th 1944.

[Tony Smith]

Never heard the name Kerrison before.

[Tony Smith]

..is marked "Predictor, AA, No.3, Mk1". Is Kerrison the Patent holder's name or the first manufacturer's name? Does it only apply to US built versions?

[Stellan Bojerud (RIP)]

Yes Sir, I can boogie, boogie-woogie all night long after seeing those marvelous pictures.

It is surely a GB made Kerrison Predictor. I think the US never made them but bought them from GB.

Instead the S.C.R 584 Automatic Gunlaying Radar was developed in USA. When Hitler started dropping not only V 1 but V 2 on London General Marschall sent 165 of these and 20 US AA Btys to GB.

Colonel Kerrison (RA) is credited as inventor of this mechanical computer.

I am sure that some of our British friends could deciphre the factory M & P. Ltd.

Thank You Tony! Your pictures have helped me a lot in my research.

Here You can see how it was deployed. The Kerrison Predictor to the right behind the gun. The sight operator standing on the gun platform. The gunlayers hadn´t to calculate speed and course but only keep the target in the middle of the "spider-web" sights. US gun North Africa 1943. (US Sight Computing M7 or M7A).

[Stellan Bojerud (RIP)]

Tony,

Is the searchlight on the picture 90 cm (35,5 inch). Reflector in glass or metal? Hand or remote control?

[Tony Smith]

The searchlight is an 18 inch model made by the General Arc Light Co, Long Island and is powered by an Onan 2 cyl 40 volt, 50 amp (2Kva) generator. The reflector is polished aluminium. Rotation and elevation is hand controlled, but carbon rod feed to maintain the Arc is automatic

[Stellan Bojerud (RIP)]

Thank You Tony. Never saw such a Searchlight before.

Here is an interesting piece. The gun carriage is MK I. The gun could also be an updated MK I (1937 type).

Anyhow the 1944 type "Stiffkey-Stick" sights and the shields have been added later.

To the left a S.C.R. 584 Automatic Gunlaying Radar - one of the 165 supplied to GB from USA in 1944 to counter the German V-missiles attack.

During June - September 1944 the AA was able to shoot down approx 1.550 V-missiles = 65%. The record was 68 shot down on one single day.