25mm Bofors


#1

The first version of the 25mm Bofors, the M/32, fired 25 x 205R ammunition. A later model, the M/38, used 25 x 187R ammunition (see: http://quarryhs.co.uk/Bofors.htm for a brief history of Bofors automatic cannon).

All of the information about the 25mm I have concerns the M/32 and its 25 x 205R ammunition. I am curious about the 25 x 187R. Can anyone:

  1. Post a photo of the round (preferably next to the 25 x 205R for comparison purposes)?

  2. Provide any data on how the projectile weight and muzzle velocity compared with the 25 x 205R?

  3. Explain why Bofors replaced the 25 x 205R with the 25 x 187R?

  4. Explain how the M/38 differed from the M/32?

  5. Tell me if the M/38 saw much service?

Any and all information gratefully received!


#2

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According to “flottans fartyg” by Törnlund & Söderlund claim that the improved M/38 ammo just had better balistics and slightly improved AA-capacity.( Where I found from the pic with the crew with cool googles)

This is Navy stuff, so I´m not shure how much data I have on it.
I have quite a lot on the production facilities improvised during 1940, but I don´t think its detailed enough.
(I know theres a map of the factory somewhere on my computer, but probably nothing on the case itself.)
I´ll give it a try…

Cheers
/John


#3

Thanks John, that’s helpful.

I have to say I am surprised they claim better ballistics from a smaller cartridge case!


#4



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History
25 mm kulspruta (automatkanon) var den första artilleripjäsen med fotavfyrning. Den togs fram av Bofors parallellt med 40 mm automatkanon för att snabbt kunna tillföra flottan en användbar och funktionsduglig närluftvärnspjäs, trots att 25 mm ansågs vara i minsta laget. Ammunitionen, som ursprungligen betecknades m/32, utvecklades och fick förbättrad ballistik och modellår 1938 med något ökad luftvärnseffekt.
Produktion-
Tillverkare: Bofors AB
Annat: 1940

Also FWIW, 25 mm HE – T Sectioned Projectile Bofors, Sweden, 1930’s


If anyone can provide a translation of the Swedish text it be most appreciated.
Thanks,
Brian


#5

It’s a direct copy of the text from Törnlund & Söderlund
a brief translation:
25 mm Machinegun (later renamned autcannon)
First (Swedish navy) gun with foot trigger(pedal)
Developed in parralle wiht the 40mm gun to provide Navy with usefull close defence AA.
although 25mm was considered to be a bit too weak.
Initial the ammo M/32 improved M/38 ammo just had better balistics and slightly improved AA-capacity.

But I beg to differ from the Idea that the Navy initially thought 25 was too weak.
Swedish navy started to switch to 40mm around the late thirties.
before that 25mm was seen as sufficient, supplementing the 57mm and 75mm “quickfiring” guns.

Cheers
/John


#6

Bofors 25 mm guns where used in four mounts:
Single and Twin fixed (mostly shipbased)
Single mobile (a few used by Coastal artillery)
Single Submarine gun (three pieces)

I found some bits and pieces that does not make things really clear except that M/38 became the standard live round in 1940.

Planned production as of December 1941,
Live (slsgr) M/38 in large numbers, 950 000 Ordered.

The exercise ammo slexPrj (sl= Trace Ex= exercise Prj = Grenade), we find both M/32 and M/38
But it does not say what case it was loaded in.

In October 1940 Stockholm naval station monthly report availablilty of live ammo
Here there different rows for M/32 and M/38
Skp = SkarpPatron "Live Case"
But small quantites of M/32.

For EOD, the German 20mm M/39 are listed after the 25mm

Cheers
/John


#7

John, thanks a lot for still keeping me in mind!!!


#8

Thank you John. I have to say that this remains a bit of a mystery. If the M/32 was in service (I have a 1936 Bofors catalogue which features four different 25mm mountings compared with two for the 40mm), why go to the trouble of introducing a new 25mm round, which would have required modified if not new guns, especially if that was about the time they started to switch to 40mm?

There’s a story there, no doubt buried deep in some archive!