Velocity? Not really. Accuracy, yes and no. A shrould that is clipping or too tight can cause accuracy problems. As is one that is not aligned correctly, even though it is not clipping.
The Good news is that a shrould that is properly constructed can act as an air stripper. And give supperior accuracy compaired to a non shrouded bbl. in a give gun.
What kind of shroud? either way it should not affect your velocity at all. I bought the hush pipe off ebay and I don’t recommend it, so yourself the hassle and buy tonys shroud, may be a little pricey but its worth every penny
Not sure which one it is. SS wasn’t on the box. Just came second had fully shrouded. It barks like a 22 LR without the shroud.