Clipper, I didn't say cutting a barrel would make it less stiff. I said cutting a fluted barrel might make it less stiff. I am perfectly aware that short fat barrels tend to be stiffer than long thin ones, and I am not arguing that point. My brother's 700 Tactical's 20" barrel is probably stiffer than my 700 VSF's 26" barrel. But hear me out for a second regarding cutting down fluted barrels...
When a heavy barrel is unfluted, it resists equally in all 360º deflections which occur at right angles to the barrel's axis. When you cut flutes down the length of a barrel, it is no longer as resistant to lateral deflection at the point of the flute as it is at the "lands" between flutes. This would be particularly true if the barrel were fluted for its entire length, right up to the muzzle. However, by tying the "lands" together at either end of the barrel with unfluted segments, the "lands" would tend to be mutually supporting against a deflection along the line of a flute. So my thinking is this: if you could cut down the length of a 26" fluted barrel by removing the middle 6" of length, then yes, the cut down barrel would be stiffer, because it would retain the raised areas at the proximal and distal ends of the barrel, tying the lands together into mutually supporting structures. But for practical reasons, that is not how it would be done, and it is my thinking is that, for the reasons stated above, the resultant cut down barrel would be, at the very best, only as stiff as the original, and at the worst, measurably less stiff.
If I were a degreed engineer in metallurgy, I could probably explain it better, but I lack the vocabulary for it. I hope that what I said makes some kind of sense to somebody. Or, I could be an idiot of the first water and be totally wrong. Right about now, I'm OK with either. My father in law, to whom I was very close, passed away last night after a long hard fight with illness, and we had been keeping a vigil at his beside for the past 48 hours until he passed. My brain does not feel particularly sharp at the moment.