Ruger mystery parts

[Acorn]

I bought a used PC Carbine in 9mm and got the extra mag well and stock spacers and wrenches as well. No box no manual.
I also received the flip up rear sight and another part I have no idea what it is.
I looked at an on line exploded view and don't see anything resembling the latter.
I figure the flip up sight is for an AR platform it is Ruger marked.

 

[Mobuck]

The flat part is the charge handle latch for an AR type rifle. Very commonly replaced with a bigger, easier to manipulate part. You're correct on the rear sight but I'm not sure it'll work on the PCC.

 

[Acorn]

Thank you sir. The previous owner must have included some extras in when he traded it in.

 

[NetNathan]

That flat piece looks like the ejector. Mcarbo and Tandemkross make better ones. Maybe that is the original and a better one was installed?