After further considering the Blue Print ( other Thread) I have come to the conclusion that this cartridge IS for the Sturmgewehr…The “Neck” of the Cartridge ( the enlarged Bullet diameter) will engage the chamber neck loosely (Being a .330 diameter) and allow the Bullet itself to engage the throat and rifling correctly. The “Oversized” Bullet (.330-.340) is a bit big for the Rifling grooves (.323") but since the bullet is Lead cored, it will engrave well. ( see WW I 8x50R fired in 7,62x54R Barrels).
The slower progress of the bullet will ensure Higher Temperature and Pressure in the chamber, ensuring complete combustion of the Nitrocellulose casing ( PV=nRT, the Gas Law relating Pressure, Volume and Temperature, n and R are Gas Constants).
The Burning Powder/Casing will also send the Primer cup down the barrel, either to be expelled with the gas, or shot out with the next Bullet. The serrations along the Case body were to increase Burning areas, so as to “speed up” the combustion. (it was Progressive, with a slow pressure build up as the inner wall burnt through (pushing the bullet to engage the rifling fully and “swage down” followed by an increased rate of burn, as the serrations were entered by the flame front creating a higher pressure, and higher temperature, to send the bullet all the way out of the barrel…It would be interesting to see a Progressive Plot (by Piezo electric means) of the “pressure curve” from Ignition to bullet exit… sort of a “sawtooth double step” (in milli-seconds)
Since the StG was for Close combat, any inaccuracies from a heavy, pointed bullet at probably a slightly lower velocity, would be negligible…Really a “Spray and Pray” result.
The Initial misconception by the British report that this was for a “Normal” chambered 7,9 German, or 8mm Breda gun is probably because they did not have full details on the SturmGewehr and its cartridge, even though Mkb42 and MP43s were already captured in Normandy in June 44 and at Falaise Gap later in July-August. Again, the “un-primed” mind of the investigators.
May be just a case of the Left and Right hands not knowing what the other was doing. Happens all the time in the Military ( and ion Civil Gov’t).
Moderator, is it possible to Combine these two Posts, as one entity, to avoid them both going astray???
Proud owner of three (3) MP/StG44s…all working for the Movies—now.