Yes, that horrible "long distance jump" .38s need to make out of a .357 chamber....personally, I think its bunk. We aren't talking about firing a .45colt from a gun cut to also shoot .410 shells here.
people will often cite the difference in the case lengths, .38 and .357, and yes, its 0.135" difference (max length specs). So, that's a big jump, right??
Except, it isn't. First off 0.135" isn't all that big a difference, but more importantly, the bullet jump ISN'T 0.135"!! its 0.04" inches, less than 1/3 of the usually quoted 0.135".
Look at the COAL lengths. .357 is 1.590" .38 Special is 1.550". That's only 0.04" difference in the max LOADED length of the two rounds. I don't see how the difference the bullet had to jump to reach the rifling can be any more than the difference between the length of the loaded rounds.
I think is likely true that jump distance is not a big concern for accuracy, at least with the average factory ammo.
I fired some 38 Short Colt ammo through a 357 revolver and it produced one of the better groups at 25 yards. At least for that ammo in that gun, jump through the long cylinder did not degrade accuracy.