It will not work due to the rail system on the HK 416 AEG.
David from USA asked:
How do you remove the front clamp
Cory from USA:
There are 3 pins held in place with a spring. You will need to get the bottom of the spring and unhook it from the larger headed pin and then remove the spring. You can then push / pull on the head of that pin and unhook the clasp, that will release the clamp.