AR15: Different pattern bayonet lugs?

[pensiveape]

[rustyx]

[pensiveape]

[ar15barrels]

-I have yet to measure them to see if there is a height difference...but is it possible or likely that Upper-B is an F-type sight even though it’s not marked as such?

Yes.
The lack of an F does NOT automatically mean it's a rifle front sight base.
It only means it does not have an F marked on it.

An F stamp denotes that it's for a carbine gas system barrel.

Measuring the height will tell you what you need to know.

[nate76239]

I think the lugs look like a manufacturing defect when the part was cast and or cut, being a budget brand they just slapped on the part anyway.

[pensiveape]

So I measured the front sight blocks and upper-B which was not marked with an “f” is indeed the standard height for an fsb (rather than f-marked). I called up midway and they said all the uppers should be identical, and they don’t know how it’s possible for that to have happened... and the abnormal bayonet lug is also on the same upper as the non f-marked sight. So I’m sending that upper back.
I’m kind of bothered by the fact that they will probably take back the upper and put it back into circulation only to resell it to someone else.

I also learned that AR Stoner is a house brand for MidwayUSA. Midway makes AR Stoner products. I learned this because I initially asked for AR Stoner manufacturer contact info (since I couldn’t find it online), and then was told that it’s their house brand and they can answer any questions.