Browning rifles have used 1 turn in 10", most Remington 700 used 1 in 9 1/4". Ruger, Sako, Savage, Winchester and others used 1 in 9 1/2". Most of the later models in this caliber use 1 turn in 9 1/4" or 9 1/2", these numbers are out of the Nosler handbook.
Back in the 1960's I bought a "244Remington" in a Remington rifle. It had a 12" twist and only liked the 100 gr. Hornady RN bullet. Several CO mulies fell to it and didn't know it was a 12" twist bbl.!
Shortly thereafter the .243 Winchester and the 6MM Remington rifles hit the market, both...
No matter the choice, practice, practice at different distances, in order to place a properly designed bullet in the area where it needs to go.
That said, I have used the .270wsm with 140 gr. bullets for some time and it does a fine job.
Jim
Bruce, I've only seen 2 of them lately and I'm guessin' it's some type of bluing on (maybe) a bluable metal coating (?) I'm not sure, as the used finish of the barrel is a very dark blue in color.
Jim