TargetTalk

I assume if I take off the barrel shroud, tape the barrel port holes with tape, reinstall the barrel shroud, this would decrease air wastage, and increase the barrel velocity?

If I then drop the increased velocity back to original untaped velocity, I would decrease the noise level?

Or is it, by taping the port holes, I would increase the velocity and make the pistol louder. And if I adjust the velocity back to original velocity, I would just get the same noise level?

I had problem figuring out this SAT question.

While in teory, pluging the holes on the barrel would increase the muzzle velocity, but the question is "by how much?"
The first hole is in the middle of the barrel, and by that time the pressure sould have decreased by a lot... so not much gain here...

Less air released equals less pressure, hence less noise.

I suspect that the catch for the stabilizer, doesn't help either... it lets some air escape when it opens.
You can reduce the amount of air fairly easy, but you should test what impact it will have on the groups.
A crony, a vise and a screw driver are all the tools required. Let us know how it went.

Hope this helps

Reduce the gas energy at the muzzle, there are 3 ways to do this:
longer barrel, approx. 260 mm
plug the ports and install the silencer
go back to CO2 (carbon dioxide)

Have a nice day and have fun

Ear plugs will do the same thing.