I have a used A1 upper receiver for sale. I do not know what brand it is, it does have a "P" & "M" under the sight adustment wheel. It does not have a brass deflector so there is a little wear on the opening of the ejection port. It has the forward assist, ejection port cover and rear sight. There is no bolt/carrier or charging handle.
I got this upper receiver included with a rifle in a trade, I'm putting flat tops on all my rifles, so I don't need it. I didn't sight in this upper when it was a completed rifle, but I did notice that the rear sight seams very sticky and it's a bit difficult to flip between apetures.
shipped. (I have parts ordered and need to pay for them hanks...