= Hmmmm.... sneaky stealthy goodness.  

Awesome.

How's it sound?

Not bad, with the wipe in place and a little coolant.  Quite a bit quieter than I was expecting from such a little can.  Louder than a "full size" suppressor, but still enough reduction to make it not sound like a pistol shot.  

Wipe is awesome for about 2 magazines, pretty good for about 3 more.  One of my favorite features of the Poseidon is the capacity to use an additional thin "wipe" in the rear... which seals the can and keeps your coolant ready to go indefinitely.

Looks like you're pretty much relegated to using a small 9mm for that can? Not familiar with the Poseiden.

Yes please!!! Is this a full blown supressor that requires license and all?

Please be good to me and tell me no.

And where did you get the threaded barrel?

Okay, first the good news.... the barrel is a factory SIG offering.  They're out of stock right now, but I ordered it a few months ago and go it right away.

http://store.sigsauer.com/9mm-threaded-barrel-for-p938-black.html

Now the not-so-good news.  The Thompson Machine Poseidon is a "real" suppressor, that is subject to NFA.  Mine is a very early version, Thompson has redesigned it, it probably works even better now.

http://www.thompsonmachine.net/?page_id=99

TX-Punisher... I've used the Poseidon on this gun, my M&P9C, and my Beretta 92... works just fine on all three.  It's so small and light, it doesn't need a booster... even on the tiny little P938 it ran just fine.