Difference between 28cm SK L/40 & 28cm SK L/45 - L/50 ?

[Tony without Kaiser]

Can anyone explain to me what the difference is between an Imperial German 28cm SK L/40 cartridge casing (Deutschland-Klasse) and a 28cm SK L/45 -L/50 (Von der Tann)cartridge casing? Both are 1220mm tall. I know cartridge casings were not filled to the top, so perhaps there more charge in one or the other? Could a 28cm SK L/45 -L/50 be fired in a 28cm SK L/40?

 

[Hoeksel]

If I recall correctly the SK L/45-L/50 has a thicker material at the bottom, indicating a stronger charge. Just wait for thekees to answer ;-)

 

[Tony without Kaiser]

That would make sense. Hopefully some more detail will emerge from Kees, Frank, and others.

 

[thekees]

The diameter of the case (bottom ) is larger too, thats why they were so clearly marked in WW2, will take measurements tomorrow.

 

[Tony without Kaiser]

Thank you Kees and Hoeksel.

So if the base on a 28cm SK L/45 -L/50 is larger and thicker, then I assume that a 28cm SK L/45 -L/50 could probably not be fired in a 28cm SK L/40, as the breech might not close?

This 28cm SK L/45 -L/50 has a base that is 11mm thick, and 324mm accross.

 

[thekees]

The L40 case is 318 mm wide, and 41 kg
The L45/50 case is 324 mm wide, and almost 43 kg
Compared with an 30,5 cm case: 52 kg and 35 cm.

 

[Tony without Kaiser]

Thank you Kees. So that is clear now; the SK L45-50 has a larger base diameter by 6mm.

Back to my final question, based on the thousands of tank rounds of various calibres I fired in 26 years in the Canadian Tank Corps, the breech has room around the casing base. What matters is the thickness of the base to ensure a proper seal. How thick is your L/40 at the base Kees?

If a L/40 casing is also 11mm thick at the base (as is the L/45 -L/50), then I see no reason why a L/45 -L/50 casing could not be fired in a L/40 gun.

However, the reverse would not apply, a L/40 casing would not be allowed to used in a L/45 -L/50 gun as the base is not strengthened adequately to withstand the pressure.

Thoughts?

 

[thekees]

Tony,

Rim thickness is all the same, all are about 10-11 mm. maybe the base is thicker, because the barrel of the gun was 10x the calibre longer, so the pressure in the barrel, and the case was much higher, the differ in the weight might declare that.

 

[charley777]

Quite tricky the new system of attaching pictures.....

Anyway here are two drawings showing the different cases for the 2 types of gun.
Mainly the rim diameter that differs.

 

[Tony without Kaiser]

Thank you Charley. Unfortunately those are so small I can't make even the "enlargement" out. Could you possibly email me those? It would be appreciated.

What book do those come out of? Thanx, Tony