Hi, I believe the mk1 verminator (or gladiator - big brother) do not have shrouded barrels. The mk2 does though.
I own a gladiator and mk 1 verminator.

Early mk1 verminators did have a brass adapter to 1/2 inch UNC male for suppressors but my mk1 is circa 2011 and has a smooth-twist barrel (only partial rifling) and does not have the brass figment. What it does have is 2 inches of extra barrel length with a capping piece to cover the manufacturing marks from making the smooth twist, which is also directly threaded for 1/2 inch UNC male. I believe this is the same barrel that lurks inside the mk2 shroud.

When I bought it second hand I was concerned that the barrel looked wrong compared to a friends earlier mk1 so I contacted the fx importer and was told the above.

So early mk1s probably don't have enough barrel past the cylinder to accommodate an airstream but later ones I think do, which would be nice so as to offset the new longer barrel.

Personally I came on here to find a custom reflex moderator on a recommendation from someone at my local range...

I hope the above info helps.