My 700 Classic has the 1/16" twist and it has always worked swell with the 200X and now the 200TTSX, but I also get great accuracy with the heavies. I'm sure that the faster speeds I get out its Ackley Improved case help. I haven't measured it, but my SILs mauser must have a faster twist. I bought that rifle from a gunshop, used, and it had a Douglas bbl in .358 Win. Since it was a Mod 98 action, I had my smith open it up to the 35 Whelen AI, using the same reamer he did on my rifle. At any rate, it shoots the Nosler 225 Accubond into bug holes too. In all likelihood, his has the faster twist used in most .358s.
I saw a dramatic difference in a Mod 1895 that was bobbed to 20", but was an older 1/38" twist (I think) and an older Mod 444, also with the 1/38. I could get neither to handle the 300+ gr cast bullets at the slow speeds I wanted ( say 1600 or so) at high speeds it shot them like a benchrest gun but both kicked the living snot out of me! I am way past enjoying that sort of thing, ha. I sold both. I think a faster twist makes a lot of sense for smaller case rounds, i.e. the .358 and for, of course, the lighter bullets most use ( and which work well indeed) the 35 Whelen for. I've killed a lot of elk sized game with the 200X, but also with the older 250X out of my 1/16". maybe my rifle is just a great one! ( which I believe it is, it has spoiled me to where it is my only bonafide personal favorite, ha. ) Good luck to you Pard. Oh yea, my above SIL shot a button buck over Thanksgiving up in Pennsylvania with his cousins Mod 336 .35 Remington and the 200 Corlokt. Perfection, ha.