I am pretty sure of the parentage. That is, I trust the person I got him from. Why silver genes? There is no white or silver on him...? Is it the pattern?
See how he's got pale creamy yellow color in his hackles and saddle, yet some darker orange showing up in the shoulders? That's both silver and gold genes you're seeing there. Black Coppers only carry gold genes (otherwise you'd see white in the hackle and saddle) and same with Welsummers. . . Either the previous owner/breeder lied or didn't actually know what they were selling.
There are Birchen Marans (silver version of Black Coppers, they have silver genes) that could create this though, but they're not common at all.