I won't speak about the Winchester but the Remington 'FBI' load does expand from 2 inch barrels, in one test at least.

158 grain +P lead HP (test 2)

Explaining to customers why their heirloom .38 shot loose in a single box of shells is something Buffalo Bore is more willing to contemplate than the larger ammo companies.

Whether that's a positive or negative might depend on whether you were shooting such a firearm, or something proofed at higher pressures.

PreWWII .38s are such SWEET shooters it'd be easy to shoot hot ammo "just this one time".. and likely not very smart.

IF you want to carry hot .38 ammo you're better off shooting it in a .357. Just for drill. In My Opinion.