Alright, I'm confused. Someone help me understand this:

According to this arrow ballistics calculator http://home.att.net/~sajackson/ballistics.html, my previous arrow that weighed 311gr has a total verticle drop of 49 inches at 40yds. I just bought new arrows that weigh 382gr and is supposed to drop 59 inches at 40 yards. Previously with the 311gr arrows, I'd hit about a foot below where I aimed with my single pin sight at 40 yards. Keep in mind the ballistics calculator says my new 382gr arrow is now supposed to drop 10 inches below the 311gr arrow. Well, it doesn't. In fact, it hits the exact identical spot. What's up?

Read the fine print at the bottom. That is total drop assuming your arrow leaves the bow perfectly level to the ground and begins dropping the instant it leaves the bow. Your's is not. Your's is leaving the bow and traveling in an upward arc on its way to the target.

well, to be accurate - his arrow does start accelerating downward as soon as it leaves the bow - its just got to get thru chewing up the initial vertical velocity before you notice.

There's one in every croud.

I understand that my arrow has an upward travel to about 18 yards at which time it starts its decent. What I don't fully understand is that although the two arrows are 72 grains apart in weight, they both hit about a foot below where I aim at 40yds.

Here's my best guess at what's happened/happening:

When I was shooting the 311gr arrow, I sighted it dead on at 25yds. When I switched to the 382gr arrow, I had to move my elevation adjustment down because the heavier arrow was dropping more causing a low poi as compared to the 311gr arrow. That's obvious I know. What's not obvious is why at 40 yards, the 382gr arrow only drops about a foot lower than where I aim. (about the same as with the 311gr arrow) If I sighted both arrows to hit dead on at 25, doesn't that mean that by the time the arrows reach the 40yd mark, that the heavier arrow should've dropped considerably more? According to the link, 10 inches more. But, that is not the case at all.

There's clearly a science here that just takes the right person to explain.

is the shaft the same size for both arrows?

where do they hit in relation at 20 yards, and 30 yards?

the 311 is a CX maxima 250 3d select fletched with 4" feathers

the 382 is a CX maxima 350 3d select fletched with 4" vanes

Shaftdiameters are 3 or 4 thousandths of an inch apart. Both shafts are 26 inches.

I have not recorded where they both hit at various ranges. Though I'm probably wrong I'm not sure if that matters so much because in the end, fact remains that they still hit about the same poi at 40yds while they are 71gr apart in weight. -SHRUGS-

it won't be so strange if the heavier shafts hit higher than the lighter ones at 20 and 30. the thicker shaft will have the arrow sitting higher on the rest - making it impact higher. its just something to check.