Depends entirely on the round used. Bullet trajectory also plays a major role of 'where the hit' will be.Originally Posted by spisam
(Edited to remove "heavier bullet will hit the ground faster than lighter bulets" - Doh! Where was my head).
If you zero your firearm at 25 yds using a 40 grain bullet, using the same zero, a 28 gr bullet will hit slightly lower. A bullet, regardless of weight, will fall to the ground at the same rate of speed. However, a 28 gr bullet will travel farther down range than the 40 gr bullet before it falls the same distance due to its increased velocity (lighter bullet, faster rate of travel). The reverse is true due to the 28 gr bullet flying at a flatter trajectory at a 25 yd zero as far as hit zone is concerned from 25 yds to 100 yds.
Thus, unless you provide more specifics, it is impossible to give accurate data at what the projectile ballistics will be once the projectile leaves the barrel.
Example: If you zeroed at 25 yds using a 28 gr bullet and try to adjust to 100 yds using a 40 gr bullet, you may encounter several inches of drop from one distance to another. If you zeroed at 25 yds using a 40gr bullet and try to adjust to 100 yds using a 28 gr bullet, the drop will be substantially less. Remember also that the bullet travels in an arc. It increases altitude at first then decreases altitude (this is because the barrel is in a slightly upward angle instead of being parallel to the ground) while the same force of gravity is working on the projectile.
Best thing to do is to re zero at 100 yds and write down the changes made to you can zero back to 25 yds for indoor use. Whatever the outcome, the hit distance elevation change from 25 yds to 100 yds will still be on paper so adjust as you go.
This does not even take into effect the distance of the sight elevation from the barrel line of sight. The above graphs were compiled using the 'stock' sighting systems.