I've seen a lot of videos and read a lot of writings lately of .357 short barrels, 9mm snubs, .38+P, .327, etc. etc. and here's my thoughts of compiling that knowledge and thinking it all over:
For .357, my cut off is 2 inches. Anything 2 and under is suspect to be more light and noise than velocity and for what you lose in that (control, follow up shots, disorientation) it's not worth it. Yes, there are loads with low flash powders and such, but the barrels are so short, you're still getting flash and likely with low flash, you're also getting lower velocity.
You want a 2 inch or shorter revolver? Shoot .38+P or better yet, get a .327. Why do I say that instead of 9mm? Because I don't trust 9mm in a revolver and the way the bullets are crimped or the moon clips. Yes, 9mm is cheap and it's great for a BUG to a 9mm pistol, and if a BUG is desired (which it is for me) I'd then say yet, but for primary carry? No sir, a standard revolver cartridge is better.
Paul Harrell's video was very good, but from the data I've seen, the .357 takes a big hit going from 2.25 to 1.875 inch barrels. Paul did not use a sub 2 inch barrel, I assume he didn't have one or he doesn't believe that 3/8" less of barrel doesn't make a difference, but it does when you consider how short the barrels are. 3/8" less is almost a 17% reduction in barrel length, so potentially you can lose 17% of your velocity OR MORE! When we're talking 1000, 1100, or 1200 fps, that's close to possibly being 200 fps LESS!
For anything over 2 inches, it's .357. It seems .357 just needs a bit over 2 inch to be effective with most ammo. Personally, I would prefer 3 inches for .357, but the question of the topic is "When is the barrel too short for .357?" and I've answered that.
For as much data is out there, I'm with Jeb Stuart: I'm sick to death of all the numbers and BS. Take a gun, go to the range, and shoot. I don't want to shoot .357 snubs because I know I can't shoot .357 snubs, so I don't shoot .357 snubs and won't buy any .357 snubs so I don't consider .357 snubs for carrying.
Maybe I could shoot 9mm snubs better, but again, I don't trust them for primary carry. .38's are the standard for snub revolvers, but I believe the .38 is rendered obsolete compared to the .327 Magnum for self defense considering the distances I'd be shooting from and the extra round in the cylinder. For self defense, you don't need the heavy 158 grain bullet, unless you're living in Alaska, not when an 85 grain .327 at 1300 fps does plenty of damage and is very controllable.
*inhales*
I don't want to put so much faith on one extra round, but fact is that it could be that one round that can stop a threat and save your life or someone else's life. A .38 is better than nothing, but if after 5 shots you haven't stopped the threat or threats and you've had to take an extra 5 or 10 seconds to reload... a life can be severely damaged or end in that time.