37 x 258mmR M34 Bofors Drawings

Why the funny “tails” on the top row for tracers? I thought those caused instability / inaccuracy.

Basically because the Swedes (or better Bofors) used to have a separate tracer igniting mechanizm as their tracers were not just lit by the propellant.

Would the flashtube extend all the way to the projectile?

No, why should it?

To illuminate the function of a tracer priming mechanizm:

Here one of the 40x311R 40/L60 Bofors as Germany made them initially as per the Bofors design (and then switched to conventional tracers).

tracer primer

So that is the “device” that was inserted into the tip of the tail in the projectile, as opposed to a simple thin metal cover over the tracer element.

I thought maybe they extended the flash tube up to the base of the projectile to make sure it ignited the priming compound.

What was the purpose of that complexity?

No, it is in the lowest point of the tracer tube. The item you see here gets blown out to the back upon ignition. (image below)

A priming tube was not all that common in the early to mid 1930s and also would have used up more resources.

When fully sealing a tracer it will have a much longer shelf life and likelier have a more reliable ignition.

But to have the true answer we should have asked this the original designer of this system.

Image source: Swedish digital museum.

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BTW, the Swedes used this system down to 20mm.

thanks, so another question, I’m 3d modeling from the drawings above and it looks totally different from the round you just showed the section of. Are the drawings from above inaccurate and in reality they look like your section?

Those on top are generalized hand-drawn overviews, in no case I would use those.
The cutaway photo here definately rules.

The drawings from TBS newletter are drawn with artistic license.

In case you are after measurements you may try one of these.

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ahhh, I understand now.

M/34 is the blunt round nosed design, m/38 and m/39 are the longer designs with the longer tails. Maybe they just added a windscreen?

What would have been the most common for a 1943 case?


Are the Polish m/34 rounds the same dimensions as Swedish?

If you want to print it

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I think a later design would be it, means the one with the ballistic cap.

Polish M34 dimensions: yes as they used Swedish licences

First print
image image

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These are frequently misunderstood in the US, as after WWII the guns were sold here legally for enthusiasts, as was the ammunition. Much of it still remains, with many not realizing that it is hazardous. You could purchase AP, APHE or straight high explosive for $3.50 a round, $3.00 if you bought in bulk. The gun was $300.00. Collectors could get just the projectiles if desired (still HE loaded). Here is an advertisement from Service Armament in Chicago, 1961. I found three (2 APHE, 1 HE) in my area in about four months. Two are shown in the picture, one of them was the projectile sold by itself. If you look closely at the bottom projo you can see that all they did was cut the case, then shape it around the base of the projectile. I wanted to know if the projectile was in fact live, so it was hit with a perf charge (shaped charge used in oil wells) that contains only 19 grams of explosive. This is such a small charge that if the round is empty you have only a small hole in the body, if live, you will get a detonation.

Picture3 Picture4


What was the polish designation for the APHE m/34 style?

Should it be yellow with red band from above (it was refinished black)

In PL standard types ammo ang gun have a designation 1936 [wz. 36]
APHE yellow [without strip]. black text markings
AP-T with strip - red colour of tracer