German 20 X 82 rimless shell case


#1
  • I have a fired (inert) 20 X 82 rimless shell case with a head diameter of 25.1 mm (0.988-inch). It is a brown lacquered steel case with an electric primer (fired). Red sealant is still visible on the primer circumference. Two flash holes can be seen inside of the shell case at the bottom. I don’t have a picture of the impressed headstamp markings but the markings are:
    “44” => Year of the shell case manufacture 1944;
    “wg” => Shell case maker “Hasag, Hugo Schneider AG, Lampenfabrik,
    Leipzig”;
    “27 7” => Lot number “27” and probably sub-lot number “7” (?) because
    there is a gap (space) between “27” and “7”.
    There is NO air force acceptance mark stamped on my 20 X 82 rimless shell case head. I have these QUESTIONS:
    1. Since my 20 X 82 rimless shell case has an electric primer, what type of 20mm gun (MG 151/20) fired this case ???
    2. Is it possible to know exactly what type of 20mm projectile was crimped to my 20 X 82 rimless shell case ??? Three long crimps are visible by the case mouth.
    3. The fired 20 X 82 rimless shell case, was it ejected from the 20mm gun inside of the aircraft or outside ???
      Thanks in advance for any help, Liviu 06/20/11 P.S. Any information about the German 20 X 82 rimless ammo with electric primers will be appreciated.

#2

[quote=“Liviu”]- 1) Since my 20 X 82 rimless shell case has an electric primer, what type of 20mm gun (MG 151/20) fired this case ???
[/quote]
Yes, it was the Mauser MG 151/20, which from 1941 took over from the MG-FF the task of being the Luftwaffe’s principal aircraft cannon. This was made in two versions, one using percussion-primed ammo and one using electric-primed (sometimes called the MG 151/20E or El). The electric-primed gun was specifically made to use in installations in which the guns were synchronised to fire through the propeller disc, as it simplified synchronisation and made it more efficient. I can go into more detail about this if you want…

In practice, the only plane to make significant use of the electric version was the Focke-Wulf Fw 190 series, in which the standard armament included a pair of MG 151/20 in the wing roots. In those versions of the plane which also had MG 151/20 guns in the outer wings, these were also the electric version to simplify ammo supply (electric and percussion primed ammo were not interchangeable, each only worked with its own gun).

As a matter of interest, one very promising experimental installation of an MG 151/20 in a belly pod was tested in a Messerschmitt Bf 109G. This worked well but required the use of the electric gun, whereas the plane’s standard engine-mounted MG 151/20 was percussion-primed. The risk of confusion over ammo loading caused the project to be abandoned.


#3

Why weren’t electrical and percussion primed ammo interchangable? Was it lacquer or something intrinsic inside of the primer?


#4

The percussion primer needed to be struck forcibly to detonate, the electric one responded only to an electric current being passed through it. The primer designs were quite different.

I recall reading of a more recent development in which the primer was proposed to be dual-purpose, but that presumably wasn’t possible with WW2 technology because AFAIK no-one did it.


#5
  • @ TonyWilliams: Thanks very much for your reply. I have one more question: When the Germans started to manufacture 20 X 82 rimless ammo with electric primers ??? In 1942 or 1943 ??? Liviu 06/21/11 P.S. I wish I could get an answer to my question #3.

#6

Production started 1941 at least since such specimen do exist.


#7

As a general rule, both fired cases and belt links were ejected from aircraft as the guns fired. This would especially apply to wing-mounted guns. There would have been some exceptions with guns mounted within the fuselage (e.g. I think that in US bombers, cases from beam guns just piled up on the floor) but I’ve never studied precisely which installations might have retained the cases.


#8

As a general rule, both fired cases and belt links were ejected from aircraft as the guns fired. This would especially apply to wing-mounted guns. There would have been some exceptions with guns mounted within the fuselage (e.g. I think that in US bombers, cases from beam guns just piled up on the floor) but I’ve never studied precisely which installations might have retained the cases.[/quote]

I believe that the Hawker Hunter plane collected the links, and possibly the spent cases in a pod which was emptied on the ground. The reason was that the ejected links got caught up in the turbulent slipstream and sometimes hit the tailplane causing damage.

gravelbelly


#9

As a general rule, both fired cases and belt links were ejected from aircraft as the guns fired. This would especially apply to wing-mounted guns. There would have been some exceptions with guns mounted within the fuselage (e.g. I think that in US bombers, cases from beam guns just piled up on the floor) but I’ve never studied precisely which installations might have retained the cases.[/quote]

I believe that the Hawker Hunter plane collected the links, and possibly the spent cases in a pod which was emptied on the ground. The reason was that the ejected links got caught up in the turbulent slipstream and sometimes hit the tailplane causing damage.[/quote]

The links only - the cases were heavy enough to fall clear.

I was answering only in the context of WW2 armament installations. In postwar planes there are some significant differences, e.g. the US multi-barrel rotary guns typically load the fired cases back into the magazine - very tidy!


#10

I believe the Panavia Tornado also retains fired 27x145B cases on board, but could be wrong on this.