For what its worth, Buffalo Bore advertises a 158 gr. JHP at 1475 fps from a 4" barrel.
I wouldn't even put that ammo in my gun.
I won't put that ammo in my guns, either, but only because I'm too cheap to buy it!
I make my own ammo in that range, and sneer at the rest from the lofty height of high velocity, 6" (or longer) barrels, N frame S&Ws, Ruger Blackawks, Desert Eagles, and T/C Contenders and Marlin carbines.
(and yes there is deliberate sarcasm involved here
)
What wimpy guns are you worried about?? I got rid of my last K frame some time back, never had, and won't ever have any smaller .357. They simply aren't up to shooting "real" .357 magnum loads. And, by "real" I mean loads that get as close to the original .357 loads as practical.
I don't blame the ammo makers, and I only partly blame the gun makers, I put most of the blame on the buying public who prefers to give up maximum performance for convenience of carry.
The truly ironic thing is that while the .357 has been reduced to a shadow of its original loading, so that it will work through smaller, lighter guns, the 9mm Luger has had more and more pressure stuffed in it, to get higher velocity for improved performance.
The two are in exact opposite situations, ironically. New .357 guns (most of them) can't handle the original .357 load levels (1500fps+), and original 9mm Luger guns (P.08, etc.) can't handle new "standard" 9mm ammo loadings (1200fps+)
Now, don't get me wrong, you should absolutely run ammo suited to your gun. I just don't agree with lowering the performance so that ammo works in all guns, light or heavy. I understand the market factors that bring this about, I just don't
agree with them. And with my handloads, in my guns, I don't have to.
With my handloads in YOUR gun, I might have to...
And, I wouldn't get too hung up over someone's published velocity figures as absolutes. They aren't. I'm sure they are what the people shooting them got, but that doesn't mean they are exactly what you or I will get, out of our guns.
Had an interesting day shooting some time back, testing 4 different .357s with the same load over a chronograph. A friend shot his 6" S&W Model 19, and his Marlin 1894 carbine. I shot my 6" S&W Model 28, and a 6" Desert Eagle. The load used was a 125gr JHP and a case full of 2400 powder, taken right out of the Speer Manual of the day, and
not the max load listed.
The difference in performance was instructive. We started with my friend shooting his M19. The gun doubled. Or might be better to say he doubled the gun. Anyway two shots were fired when only one was intended. The chrony said 1620fps!
At that point, we decided to discontinue shooting that load in that gun. The four unfired rounds fell out normally, but the two fired cases had to be driven out of the chambers with a rod and a small mallet. Finger pressure on the extractor would not move them.
Next we moved to the Model 28. 6 rounds fired normally, pretty hot, but normal operation, including ejection. Velocity 1670fps!!
Then to the Desert Eagle, 9 rnds (full magazine) fired normally, function in all aspects was flawless. Velocity 1720fps!!!
And the Marlin carbine also ran flawlessly, with the 125s hitting 2200fps at the muzzle.
In this case, 3 different pistols, all with (nominal) 6" barrel length, produced 100fps difference in velocity spread between them, and one of them proved unsuitable for that level of ammo.
I mention this to show that what you get and what someone else gets from a given barrel length can vary with the guns used and 100fps difference, while uncommon, isn't impossible.