Luftwaffe Cannons & Machineguns.

[Panzerknacker]

Cardboard slevees actually.

My dear Comrade: in my extensive collection and research in the german newsreel Deutsche Wochenschau as well in other non-public instructional Lehrfilm I ve found little of the materiel you want.

Most you can see inboard footage of machineguns or like MG 15, MG 81, MG FF being fired by a bomber gunner mostly against ground targets.

The most close to your request is some footage of the MG 151 firing from the wing of Junkers Ju-87D-5 in a woche of 1944, and the Ju-87G of Rudel being filmed using its guns from a chase plane.

http://www.youtube.com/watch?v=WRUj6RiCj4w

So far I ve found no film of any Luftwaffe weapon being tested in the ground.

[tankgeezer]

Here is a pic of part of my ammo stash showing the sleeves in which they were packed This is 20x138B ammo, as used in German AA guns (and AT rifles)

[Panzerknacker]

Must be a hard work to emsemble all the magazines when you got to extract every single round from its package, but I guess with fused ammo there was no much options, you need to protect it from the shocks of the travel to the front.

[tankgeezer]

The tubes were just to prevent scratching, denting, etc. the outer crates were the real protection, whether wood, or metal. Sometimes the ammo was placed inside a sealed tin, then inside a wooden crate. Fuzes were not much trouble, being fairly simple in that size.(at the time) Physical protection of the fuze was more the thought than preventing premature functioning.
It was (in the American services anyway,) common practice to assemble belts, and magazines from loose ammo sent in bulk containers. I'd guess it was a time consuming job, but one that was really important to weed out substandard rounds. also the loads were determined by the work to be done, all A.P., all explosive, trace or no trace, even accounting for the different types of these munitions.