It's blued. The matte finish is just achieved by not polishing the parts and instead leaving them with the tumbled finish. Pretty much the same as if you sand blasted the parts and then blued them.

You really need to go with stainless steel in that environment, but even it will be subject to rusting over time if not cared for. I would imagine you could order a SS Scout through Savage's custom shop if you're dead set on that specific model.