Do you have adjustable sights, both windage & elevation? If you do, then you can adjust the sights to whatever ammo you choose. If not... you must adjust the ammo to the gun. I'll explain. Most handguns have driftable windage adjustment, but usually only target models have elevation. The best ammo is the one that hits where you aim. Lighter bullets will impact lower than heavier ones. If you cannot adjust your rear sight elevation to your point of impact, then you can compensate by experimenting and finding out which weight bullet impacts closest to where your sights are regulated for elevation. Don't worry about hitting left or right, you can drift adjust your rear sight for that. But to hit where you aim elevation wise, you cannot adjust your sights up & down, so you need to find out what weight bullet your gun "likes" for the sights you have. You can try sight swapping, with differant heights, but that's expensive (why they invented adjustable).
For example, my Kahr CM9 hits 8" below point of aim at 15yds with 115gr 9mm ammo. That's way too low to compensate for by "stacking" the sights (not aligning with top of front sight even with top of rear notch, as they were designed for, but holding so front sight is above top of rear, raising point of impact). I either needed to replace the rear with something much higher, or try a differant bullet weight (heavier) to raise point of impact. 8" at 15yds is a lot, so I skipped the 124grs, and went right to 147grs. Perfect. Point of impact at 15yds is 1" above point of aim with Winchester 147gr JHPs. I was able to change the point of impact 8" at 15yds, just by switching to heavier bullets. Never touched the sights.
If it was hitting low with the heaviest bullets, I'd have no choice but to replace rear sight, or just "aim high".
Why is all this important? The best load for your gun, bullet weight wise, is the one you can put on target. The best super-duper ultra-expanding zombie-killing hollow-point bullet made, isn't worth crap if you cannot put it where you aim.