I thought you were asking how to make it work? Those are my 2 ideas! Build you a clone, the top pick should be similar! If you don't find that, certainly you could do something to a standard forend!
I'm guessing "Best Good Friend" had it on a longer barrel?
Might look at builds of Colt 9mm SMG!
Always liked these...
If those dont fit, dremel to the rescue!!!
No cycle! But learned there is a new CCI Quiet Semi-Auto, it's a little hotter!
What's funny is one round I swear didn't fire, the sound of the hammer dropping was like 105db!