Bullets all fall at the same speed but the faster they go the farther they go before hitting the ground. If you dropped a bullet from your hand at the same time you fired the gun (if the gun was level) they would both hit the ground at the same time. The bullet starts falling the instant it leaves the gun, it is just a race to see how far it can go before falling all the way down.
My personal protection rounds of 9mm only have 125gr and that is a little more than my practice rounds at about 115. I would hate to be standing behind someone if they are shot with a 147gr load, it would likely go right through them, but then you wouldn't have to shoot twice. The report would scare anybody away.
” If you dropped a bullet from your hand at the same time you fired the gun (if the gun was level) they would both hit the ground at the same time”
Not a mechanical engineer or a physicist, but your statement would only be true in controlled conditions.
Depending on the round, for example, they can tend to gain some altitude as they fly, and as the velocity slows they drop. The air has a lot of effect.
Now if you did it in a vacuum, your assertion would be more accurate.