Pak 40

[LUQ]

Ok ,in Marder section ,Pak 40 had L46 barrel long on Marder,but in Pz 4 g,h ,Hetzell and stug 3 is L48.So what is the thruth with this 75mmL46 is he real?

[cbo]

Originally Posted by LUQ

Ok ,in Marder section ,Pak 40 had L46 barrel long on Marder,but in Pz 4 g,h ,Hetzell and stug 3 is L48.So what is the thruth with this 75mmL46 is he real?

The L/46 is real as are the L/43 and L/48. But in reality, there are only two different barrells.

The calibers length (the L/xx figure) is not only the length of barrel, but includes the chamber and it is measured differently in different countries. The Germans measured the calibers length from the rear face of the breech to the end of the barrel, not counting the muzzle brake (E in the drawing below). In the USA, calibers length was measured from the front (or inner) surface of the breech block to the end of the muzzle, not counting the muzzle brake (C in the drawing below).




The PaK 40 L/46 and the KwK 40 L/43 used the same "barrel", i.e. the rifled part corresponding to B in the drawing above. This was 2470,5mm long.
The chamber (A) of the PaK 40 was 729,5mm long while the breech recess (D) was 250mm, making the calibers length 3450mm/75mm = L/46. The KwK 40 L/43 had a chamber length (A) of 507,5mm while the breech recess (D) was 255mm, making the calibers length 3233mm/75mm = L/43.
The KwK L/48 used the same chamber of 507,5mm and the same breech recess depth of 255mm but a longer barrel of 2852,5mm for a total length of 3615mm/75mm = L/48.