While attempting to locate a more economical way to add a light/laser to a H&K Mark 23, someone on a more popular H&K board had this to say:
Surefire makes an adapter that will work with the X200A/B light. Theoretically it should work with others such as the M6 light/laser combo and the M3 light.
Board member/dealer "Bright flashlights" on www.ar15.com would be your best source for information regarding this product. Look for him in the equipment exchange. He's a top notch dealer, I've bought a lot from him.