12" twist is just fine for all bullet weights in .358, and a 14" would likely do to 280 gr. through 300's. A 16" twist, if unstable with specific bullets at 200yards, is unsuitable with those bullets at any range. The problem stems from being almost unstable at close range(even though they may hit point-on on paper. This almsot instability translates to instability and erratic behaviour (tumbling and/or turning) upon impact with heavy meat and bone.
: I've never built up a .35 Whelen as when Remington brought out that wildcat as legitimate I was already shooting .375 '06 IMP and a 9.2x62, which were virtually peas on a pod except for bullet side. When I picked up the Husky in 9.3x62, I'd already re-chambered my .367/06IMP to 9.5x68, so I used my IMP brass for the 9.3x62 by simply necking it down for the smaller .366" bullet. The IMP '06 brass fit perfectly and fireformed without loss.
: How many today realize the groove diameter of the .358 is the bore size of a 9.3, which has a groove diameter same as the bore of a .375?
: I've never owned a .270 Win. I had smaller varmint rounds of better range, and larger big game rounds better suited to British Columbian game.
: "Once when hunting hares, my Spaniels flushed a tiger, thereafter I alwasy carried one barrel loaded with ball" "When pursuing the spotted buck, I once tread on the tail of a tiger". Lt. James Forsyth, 1858.
: While tigers are quite rare around here,(beavers eat them, I've heard) grizzlies aren't.