I can't remember what happens with lighter bullets and the same bullet charge, do they raise the point of impact or lower the point of impact? Example, DD's 250 grain bullet as oppose to his 200 grain bullet.
The lighter bullet will exit the muzzle a mite sooner with the same powder charge. The gun will be in recoil. The barrel will have moved thru less arc by the time the bullet exits. Lighter bullet will hit a little lower, all things being the same. Further out, the two will cross and the heavy one will be lower. Depends on how far your target is, I guess. . .
DD-DLoS
Dick has it right.
I will add, that at reasonable pistol ranges, velocity or type of powder has very little to do with changes in POI. It is strongly dependant on projectile weight.
The first two guys covered it well. I concur. I tried in vain to get different weights of bullets to print to the same POI in my 357 mag. I loaded up both fast and slow light bullet loads (110gr) and fast & slow heavy bullet loads (158gr) with different powders and no matter what powder or charge weight I used (this was smokeless) I could not get the two different weights to hit the same. It was always light bullet lower than heavier bullet.
My experience with .45 caliber Vaqueros has been that I can make bullets anywhere from 318 grains to 123 grains hit to POA or very close.
VELOCITY is absolutely important to this.
As built, a 5.5 inch Ruger .45 will shoot a 250 at 750fps very close to POA. Lighter bullets must be shot SLOWER. A 200 shot at 650fps will be about perfect. Even a 120 can be shot almost to POA, (a little low) at about 550 fps. When you go to heavier, harder kicking 318 grainers, they have to be shot a WHOLE LOT faster to get em out of the gun at that same point of arc in recoil needed to match that 250 at 750fps. How much faster? try right around 1250 fps!!! (ruger only pressures).