Need help to identify this piece. Tool or gun part?

[jawc2]

Can someone help me to identify this piece.  Not sure if it is some kind of an old tool or a part of an old gun.  Thanks for any help.  It is marked Pat. D and has a date of May 9, 1876.  Also marked manufactured by ??? tool co.

[maxine*j]

Go to this digitized Patent Gazette.  Scroll down to Page 891 (page number printed on original Gazette) to "Titles, Drawings ^ Claims of Patents Granted May 9, 1876" and look for your item:

https://books.google.com/books?id=OtI1AQAAMAAJ&pg=PA887&lpg=PA887&dq=patent+may+9+1876&source=bl&ots...

[jawc2]

Thanks.

[tryno2]

It's an old shotgun shell primer

https://www.ebay.com/itm/Antique-12-Gauge-Shotgun-Shell-Primer-Seating-Tool-/333085647829