You now have it zeroed at 25 yards that doesn't tell you much about where it will hit at 100 or farther. You don't say, but I assume you're shooting an AR. Compared to other rifle designs the sights are much higher than the bore with an AR. AR's have the sights about 2 to 2 1/2" above the bore. Most bolt rifles 1" to 1 1/2" above the bore. So a 25 yard zero with an AR will be 2-3" high at 100. At 200 yards you should be 6-8" high and dead on at 300 yards. If you were previously zeroed at 100 yards then you should be 2" low at 25 yards.
When changing bullet weights, or even bullet designs within the same weight point of impact could change considerably. Or very little. A lot depends on the individual rifle. And it isn't unusual for heavier bullets to impact higher at close to moderate ranges than lighter bullets. Every time you pull the trigger the barrel on your rifle moves upward slightly during recoil while the bullet is still in the barrel.
Heavier bullets recoil more, which means the muzzle will rise more. To be honest this is usually more noticeable with handguns, but it does happen with rifles. If your scope isn't mounted perfectly level, you are canting the rifle slightly to one side and may not realize it. That means that at longer ranges the bullet will drift to one side. Getting the scope mounted perfectly straight is important at longer ranges whereas you may not notice at 100 yards or less.
