Everything matches alright but that is a sub-gun flash hider... This is the one you want to be looking at:
45 flash hider, HK 45 flash hider - HKPARTS.NET
Otherwise go do a search for Autoburst Technologies. Vito has some pretty cool ones last I knew.
Another option: You could probably save some money buying about any style of airsoft flash hider as they are 14mm CCW and get a 16x1mm LH tap to ream it out. Not sure how easy the taps are to find tho. I've had a hell of a time trying to find a 14.5x1mm LH tap. All the ones I am finding are custom order and over $100 just for the tap in my case.