autogun

Military Guns and Ammunition

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This is intended for people interested in the subject of military guns and their ammunition, with emphasis on automatic weapons, particularly in larger calibres (12.7+mm).

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25 mm Bofors VLD!   Ammunition 20-57mm

Started 16-Jun by autogun; 312 views.
autogun

From: autogun

16-Jun

I recently spent some time trying to find out why Bofors modified the cartridge for their 25 mm M/32 AA gun, shortening it from 205 to 187 mm to create the M/38 cartridge, and apparently reducing the MV from 900 to 850 m/s. Light dawned when I learned that the M/32 mm case was loaded with rather short shells with poor aerodynamics, whereas the M/38 had a 17 mm longer and much more streamlined shell. I can only conclude that Bofors decided that they needed to improve the ballistic shape of the shell and that it was worth shortening the case (to keep the overall round length the same) and losing some MV to obtain better long-range ballistics.  

Ironically, most 25 mm Bofors rounds in captivity seem to have the 205 mm case with an M/38 projectile stuffed in it - including mine, as shown below next to an M/38 drill round  blush

 

TonyDiG

From: TonyDiG

16-Jun

Do I understand you correctly that you now believe that the M/32 and M/38 cartridges could be used with the M/32 gun with no changes?  Have to take a look at my 40 mm book to see how the pawls engaged the cartridge.

autogun

From: autogun

16-Jun

TonyDiG said...

Do I understand you correctly that you now believe that the M/32 and M/38 cartridges could be used with the M/32 gun with no changes?

Not with no changes - a new barrel would have been needed with a chamber shaped around the smaller cartridge case. That's about it, though, with the possible exception of sight modifications to allow for different long-range ballistics.

After the changes had been implemented, Bofors kept the M/32 designation for the gun - M/38 was only used for the ammo.

 

Farmplinker

From: Farmplinker

16-Jun

Good thing it's fired in an auto. Out of a bolt gun that would be the hardest kicking DMR round ever!;)

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