I'd go with the bead blast, I personally would have said do the polished stainless. But... then I read the post about the reflective barrel, which is something I never thought about. I guess I'll be doing bead blast on my 6mmBR build also lol.
Chas1,sounds like a great build,i too had been contemplating the same decision as you for my current build, i am using a lawton 7500 s/shot it has more of a brush/satin finish than the bat(i think), it would look great against the timber,i don't think bead blasting would do it justice,go for a brushed or polished look, besides you will be too far away for the game to spot your barrel reflection.Good luck with your build.