A friend called them Texas yellow bellied fish snakes, not sure if that is the official name or not. They do eat fish in our irrigation reservoir so I do shoot them anytime I see them.
Funny thing about these snakes, any time I have shot a rattle snake they quit moving, you have to cautiously poke them with a stick to make sure they are really dead. Some of the fish snakes come out of the water when hit. The ones that did that were almost to shore with a catfish in the mouth. 
So many beneficial snakes here that compete with rattlesnakes or actually eat rattlesnakes, they all get a free pass from me.

"With this bolt-action pistol, I would keep a constant grip on the fore-stock and work the bolt with my Right-Hand, (twisting the gun inward with my Left hand and 'bolt lifting' with my free Right).

This rig would actually work pretty good for me."

I guess that would work pretty well. I was just comparing to the Savage Stryker or Striker pistol.
Looked it up and saw Striker spelled both ways on guns for sale, I think Striker is correct. They were made by Savage.