When WW2 ended, there were discussions on how to best move on with the traditionally awkward DP-28. The answer was to use belt, after all, it's easier than carrying a bunch of disc size pan mags, right?
The solution was clever, by having a belt fed adapter onto the DP-28, it can accept belts and in a pinch, can be removed to accept pan mags, but battlefield doctrine tends to stick to just using belts all the way anyway.
H3 doesn't like belts very much but having 100 round of drum mag is better than 47 round of pan mag.
Functionally it's a DP-28 but with bigger magazine capacity by using drum and featuring a top cover system.
Model reworked by Wolfosito, some texturings done by me.