The GG&G HK MK 23 light and laser mount is the the easy and rock sold way to mount a light or laser to your HK MK23.
Popular Airsoft - News: TM MK23 CQB Version Primary Airsoft HPA Adapter Warduck Edition Phew! That's a long one but it is interesting how this MK23 CQB Version Primary Airsoft HPA Adapter
MK23 / SSX23 HPA/MP5 adapter with magazine – Primary Airsoft
Nine Ball TM MK23 SOCOM Metal SAS Outer Barrel with 14mm adapter - Airsoft Extreme
A couple of guys on hkpro decided to do their own mk23 pic rail adapter, and it turned out great! : r/HecklerKoch
Accessories For New Mark 23 (Light and Suppressor Choices) | HKPRO Forums
Download STL file STANDARD MK23 to MP5 Adapter • 3D print design ・ Cults