I'm pretty sure the .358 Norma was never turned into an Ackley Improved ctg. Of course, there are .358's on the Winchester 2 1/2" case, .358's on the .300 Winchester Mag case and .358's on the full length H&H case.

The standard 2 1/2" mag case was the base for the .358 Ackley Magnum IIRC.

I think my BRNO had a 14" twist but not sure - it could have been 12". It was exceptionally accurate with 3031 (62.0gr.) and 250gr Speer Spitzers. With a 12X scope mounted, I shot several 1/4" and sub 1/4" groups that day with that combination - shooting against a 6x47 heavy varmint rifle - all 5 shot groups. My BRNO beat him group for group that day. Yes - that was "wild" to the extreme. Sounds like BS - but it isn't - I was shootng with Alex Bulhman, a retired cattleman turned Bench Rest competition shooter.

The .358 Norma is a perfectly balanced ctg. imho, of course.(but I prefer smaller ctgs. these days)