With standard primers, 3.0 grains of W231 behind a 148 gr HBWC may be a little light but should be just fine with the 3.4 gr W231.
Just remember, driving HBWC too fast may cause the skirt to become separated from the rest of the bullet. The skirt may then become lodged in the barrel. So, careful shooting and work up is necessary.
I feel Hornady is just lazy and with 357 Magnum just uses the same primer for all their testing. Magnum primers are not necessary to ignite W231 but it has no ill affects either if the loads are within published limits.
At the low end for 357 Magnum load, it will probably have a smidge more powder than the same bullet/velocity combination in 38 Special due to the larger case volume once the bullet is seated.
I have also found when shooting low power loads for optimum accuracy, the publish data and what is needed to prevent a bullet stuck in the barrel are not the same. To get Titegroup to drive a 148 HBWC out of my 4" and 6" S&W K-frame revolvers, I had to exceed the publish load data on the powder container. And even then, the velocity of my loads then barely matched the minimum velocity posted on the printed data.
My "over charged" 148 HBWC loads were well within the loads for bullets such as BBWC bullets and not anywhere near maximum for the cartridge.
The point is, working at the low end of powder charge data requires similar vigilance as working with maximum loads. But, the things to look for will be a bit different.