My .38 load is VERY mild, 105 grain SWC at 900 fps. Yeah, it hits a lot lower than .357 stuff I shoot. And, I don't think there's a factory load equivalent. I mean, it's weak, wanted it that way to simulate .22LR. It's amazingly accurate, though, to 50 yards. That bullet, sized to .357, works well in 9x19 light loads and in .380, too. It's a good mold.
There is rarely a rhyme or reason why one load shoots to a different POI than another. You'd think, heavier bullet, higher impact and that is sometimes the case in, say, a .38 special with a hot 110 grain JHP vs a hot 158 JHP. But, I had a Security Six once, shot 2" low and 4" LEFT of my .357s! Now, tell me how THAT works. I never did figure that one out. Wound up trading the gun. It's the only one that changed windage between loads that I've owned. There might have been something wrong with it, don't know, but it timed perfect, was tight, couldn't see anything wrong with the gun. It just shot weird. Wasn't particularly accurate with .38, either.
Now, my Taurus 3" 66 shoots a +P 158 maybe an inch higher than a .357 magnum 140 JHP hot load. It shoots the wadcutters an inch LOWER. My SP101 shot same POI with .38 wadcutter, .357 magnum 125 grain to 180 grain hot loads, and the +P 158, same point of aim and dead on. It was a 2.25" gun. I'd kept it, but I'd promised my SIL I'd sell it back to him when he got back from Iraq. I gave him 250 for it, more of a loan than a purchase, kept the gun for a year while he chased "hodgies". He needed the money and was going to pawn it. But, it's really rare to find a gun that accurate and that hits POA with everything you feed it... WEIRD.
There are no hard and fast rules to POI/POA, I've learned, over the years. Just shoot the danged thing and see how it shoots.