Well,
I'll add to my own post here..............
I got a line on a Marlin Camp-9 barrel and will ream it to a .356 TSW.
My Camp-9 has the 16.5# Wolff spring in it and feels much better than the stock 11# Marlin.
I'll put the 21# spring in it that Wolff offers (same one that's in my Camp-45) and a new buffer from Black Jack Buffers.
I think it will be safe, it handles my hot .45 ACP loads beautifully.
I believed I've addressed all the safety issues of recoil to any possible dangers of this combination since this is a "blowback recoil operation system" and not a " locked-breech design system".
I know the barrel/chamber is thick/strong enough due to the fact that there is much more metal surrounding the case than the .45 ACP and a stock S&W pistol barrel of this caliber.
I'll keep you all posted.
Regards,
BM1