Is an adjustable gas block even needed?

[SDW]

Bootleg ABC acts like any other BCG, just with a restriction shaft with different openings to control gas flow into the Stoner Internal Expansion System of the AR15.

Excess gas is vented like any other Stoner BCG.

Thanks. So it simply restricts flow (as opposed to "dumping" it somewhere, somehow), like most adjustable GBs on the market. Interesting idea. It has four settings, one being specific supposedly to suppressor usage. Might be marked with an "S"? Is this setting the most turned down/restrictive of the range? Some of the opinions I've read state that with just four settings, as opposed to an "infinite" range of adjustment like an AGB, it's not the best device for tuning your recoil system to various ammo. It's said this the ideal application is confined to a rifle that wears a suppressor on a sometime basis, and that's mostly it. Would you say, from your experience with yours, that this is overstating the "limitations" of this ABC?

Last and least, can you close the dust cover on this BC? I've read that you cannot. The mfr doesn't seem to mention it one way or the other.