Preheat the oven to 400°F. Toss the shrimp with the olive oil and arrange on a large rimmed baking sheet. Season with salt and pepper. Roast for 8 to 10 minutes, until cooked through.
Combine the butter, shallots, garlic, lemon zest, lemon juice, vinegar, and tarragon in the bowl of a food processor and process until smooth. Season with salt and pepper, to taste.
Spread the butter mixture over the cut sides of the bread and place, buttered side up, on a large rimmed baking sheet. Bake for 10 to 12 minutes, until the butter is melted and golden brown. Arrange the shrimp over the top, then cut the bread into 1-inch thick slices and serve.