Birdsong is a company, I don't recall where, back east someplace. Black T is one of their trademark finishes. It's kind of a cross between bluing and parkerizing (best description I can come up with). They did a bunch of FBI guns back in the day. Most of the early Kahrs had the Black T finish.
I and a couple others at the PD I worked at sent in firearms for the finish. It's quite popular. Very durable.
In Memory of Paul "Dietrich" Stines.
Dad: Say something nice to your cousin Shirley
Dietrich: For a fat girl you sure don't sweat much.
Cue sound of Head slap.
RIP Muggsy & TMan
"If you are a warrior legally authorized to carry a weapon and you step outside without that weapon, then you become a sheep, pretending that JOCKO will not come today."