Virginia Patent Book 4 ("Cavaliers and Pioneers, Abstracts of Virginia Land Patents and Grants, 1623-1800," 1934)
The "Wm. PEYNTON" mentioned in the grant, seems to be the William PEYTON on pages 12, 13 of PEYTONs Along the Aquia. The creek mentioned, Chopawamsic Creek, is in Prince William County, Virginia and is where settled the HARRISON family who married into the PEYTON family of Prince William County. See the maps on pages xiv, xv of the aforementioned book for Chopawamsic Creek.