Ich werde mal einen Post auf Englisch machen. Wer hier schon aussteigt: Dieser einfache Mod kann bei einer Mp5k 10-60 fps mehr bringen.
This easy mod can give you 10-60 fps on a Mp5k. Especially when you have an old often used or second hand one. I tested this with one from Marui.
Remove the Single Point Sling Bracket from your MP5K by removing the two pins. You should already know this if you do not charge your battery in the AEG.
The round knob on the Sling Bracket pushes the gearbox into the hop-up unit and prevents the gearbox from moving backwards. Air will leak out and pressure will be lost between the Hop-Up-Bucking and the Nozzle if the Gearbox is not pressed enough against the Hop-Up-Unit.
You can test it like this: Mark the Knob of the Sling Bracket or the Gearbox with water-soluble pen and attach the Sling Bracket.You should get an impression on the other side.
If not you should really do this mod. Take a small piece of rubber (e.g. from 2x a flat rubber band, called "Rexgummi" here), cork or some other material that can be slightly compressed. I used 3 mm cork. I pricked a slice out with a 10 mm hole punch. It perfectly fits the knob on the Single Point Bracket:
Put a square sheet will also work. Hope this mod can help you. Would be nice if you post your results here before and after. Mine with a ~M100 Spring: Before: 248 fps - After this Mod: 306 fps!