200 grain .38 Special?

[Jack]

I wonder how he 'knew' that his 200 grain load would tumble when it hit flesh? That sounds to me more like a 'guess' than a 'know'.
Back in Thee Olden Days, when jacketed pistol bullets were relatively new, most of them didn't expand much at typical non magnum pistol velocities. BTW, 30 years ago or so, I tested a whole bunch of jacketed pistol loads for expansion in various medium, so I'm working from a 'know' rather than a 'guess'.
One classic old load was the 'backwards wadcutter'. A hollow base wadcutter was seated with the large hollow base cavity pointed out- and that load would expand at typical snubby velocities.
Today, things are quite a bit different. There are lots of loads and components designed to work at non magnum pistol velocities, and most do. One of the first ones was the Winchester Silvertip bullet, and that's still around. Many of the new technology bullets, like the Hornady XTP and the Speer Gold Dot, also work at lower velocity. I believe it's Speer that makes a 135 grain load specifically for snub nose 38's.
Something else to think about: most snubbies have fixed sights. One thing you want to do is find a load that shoots to point of aim, as you found out with your Vaquero. You'll have to try the 200 grain bullet to see if it shoots anywhere near POA.
As far as stopping power, the 200 at snubby velocities wouldn't be my first choice- I'd try some of the current bullets like the ones mentioned - most are available in weights of 158 or less.