Heer’s a thread to answer this question (see link).

**The Patronentrommel 34**

This was a 75rnd double MAGAZINE designed for the Mg34 (pic 1).

Which the answer is confusing as

**The Gurttrommel 34/42**

A 50rnd BELT in a drum container (pic 2).

1) https://twitter.com/hydedefinition/status/1355176061768757254

The Patronentrommel 34 had been used on the Mg13/15 from 1931, and was subsequently altered to fit the GPMG34.

It’s purpose (a magazine) appears to have been primarily AA, as the Mg34 feed mechanism could not cope with pulling vertically dangling belts of ammunition.

2)

Yet it was problematic as it was difficult to load the magazine without a Trommelfüller (loader - pic 1) & required a separate Deckel Mit Trommelhalter (top cover on the Mg34 - Pic 2) to attach it to.

3)

So, by the end of 1938 the Patronentrommel 34 & accessories had been officially withdrawn.

Although, it still did see limited use throughout the War (primarily in the AA role), particularly with armoured units.

4)

In 1939 the Gurttrommel 34 was introduced that incorporated a 50rnd belt & designed for the Mg34 to be used in the assault role.

These were amended for use with the Mg42 & transported in a double carrier (pic 2).

And that’s what the original incorrect answer refers.

End)