Looks like mine. As far as I tell this is one of the Numrich 16" barrels.
I won this in the forum raffle a few months ago. I haven't fired it yet, I haven't been to the range in months. I have noticed that while the toggle closes all the way the extractor hits the end of the chamber and is pushed up slightly. I suspect that if I tried this with a standard recoil spring the added mass of the barrel might inhibit function.
One of these days I'll try it out.