Folks, have some questions regarding manufacturer ballistics...

1) I assume the shooter and taget are on level ground, at the same height from the ground, yes?

2) The nature of bullets is that they slow down out of the barrel, and thus drop.

3) Unless physically above the target, one wouldn't normally aim down (for the most part) at a target.

That being said...why does Hornady list the 6 out of 7 of their .270 ammo as dropping 1.5" AT THE MUZZLE? Winchester and Federal both have ammo dropping at 50yd that's zeroed at 100yds. This would seem to apply that the shooter is NOT at level with the target when the bullet leaves the gun. Or, am I missing something?

I'm asking because I've charted some of these rounds, and seeing the lines drop, then come up...I am confused.
Obviously there's some physics invloved that I'm missing, or the manufacturer's assumptions are not clear. It's clear that a bullet would drop AFTER the zero distance....but before the zero?

Help!

Thanks

jonas

Folks, have some questions regarding manufacturer ballistics...

1) I assume the shooter and taget are on level ground, at the same height from the ground, yes?

2) The nature of bullets is that they slow down out of the barrel, and thus drop.

3) Unless physically above the target, one wouldn't normally aim down (for the most part) at a target.

That being said...why does Hornady list the 6 out of 7 of their .270 ammo as dropping 1.5" AT THE MUZZLE? Winchester and Federal both have ammo dropping at 50yd that's zeroed at 100yds. This would seem to apply that the shooter is NOT at level with the target when the bullet leaves the gun. Or, am I missing something?

I'm asking because I've charted some of these rounds, and seeing the lines drop, then come up...I am confused.
Obviously there's some physics invloved that I'm missing, or the manufacturer's assumptions are not clear. It's clear that a bullet would drop AFTER the zero distance....but before the zero?

Help!

Thanks

jonas

The scope sight sits about 1.5" above the bore line...so at the muzzle the bullet will be 1.5" lower than the center of the scope. Which means that to be "on" at say 100yards, the bore line is angled slightly upwards to make up for the bullet's low start.

Iron sights are usually figured at .75" above the bore line...adn some scopes (due to the height of the rings and other factors) can be 2" or more above the bore line...which complicates matters.

The scope sight sits about 1.5" above the bore line...so at the muzzle the bullet will be 1.5" lower than the center of the scope. Which means that to be "on" at say 100yards, the bore line is angled slightly upwards to make up for the bullet's low start.

Iron sights are usually figured at .75" above the bore line...adn some scopes (due to the height of the rings and other factors) can be 2" or more above the bore line...which complicates matters.


Seriously? Man....long day. Big DUH.

Sorry for the dumb question.

I had the distinct feeling the answer was going to be embarrasingly obvious.

Going to stick my head in the sand now.

thanks

Jonas - Don't put yourself down that way. We all find things out one way or another. You don't ask you never learn. Some of the self-proclaimed experts have done far worse. I(still a learner) use to do stupid things like pulling bullets from 35 Rem cases, reducing the powder content and firing them - could have had one lodge in the bbl of my Marlin 35 and would have shot to blow it out. There have been other things - some just don't admit to their blunders. Some of us are just lucky. We all learn.

Jonas - Don't put yourself down that way. We all find things out one way or another. You don't ask you never learn. Some of the self-proclaimed experts have done far worse. I(still a learner) use to do stupid things like pulling bullets from 35 Rem cases, reducing the powder content and firing them - could have had one lodge in the bbl of my Marlin 35 and would have shot to blow it out. There have been other things - some just don't admit to their blunders. Some of us are just lucky. We all learn.


Well, that's one way to look at it. It'd be nice if the ammo makers actually stated their "givens" for ballistic tests. Not all use the same distances, long or short range.

You'd figure there'd be standards. Oh well.

Now, having accounted for a muzzle at -1.5, the simple ballistic charts actually make a bit more sense. Who knew Microsoft's Excel would actually be use for some thing fun?

Live and learn , right? Just wish it didn't have to be something so obvious!! :)

cheers

jonas

Jonas:

Yes, the bullet starts to drop the instant that it leaves the barrel. That’s because at that instant, gravity can start to pull the bullet downward, not because it’s slowing. Also, think of exterior ballistics like you would think of throwing a rock at a target, the same height as your head, using a sidearm-pitch. The rock leaves your arm at shoulder height, rises above your head and line of sight, and falls into the target.

Darrel

Yes the bullet starts to drop as soon as it leaves the barrel, I had some one argue with me once that the bullet acually starts to rise when it left the barrel for the first 50-100 meters.

Yes the bullet starts to drop as soon as it leaves the barrel, I had some one argue with me once that the bullet acually starts to rise when it left the barrel for the first 50-100 meters.


Gets easier to understand if you seperate horizontal velocity (the speed of the bullet) from vertical velocity (the speed of gravity). Keep the two seperate and it strats to make sense.

No matter how much horizontal velocity you give somthing, it has no effect on the vertical velocity...gravity just tugs at it at the same old constant rate.
----
No matter how fast a 300 pound man runs, he still weights 300 pounds. Bullets are like that, no matter how fast you push them, gravity tugs down at the same rate.

Now run that fat man off the edge of the Grand Canyon. He's going to fall as the same rate no matter how fast he was running when he went over the edge...but the faster he was running, the farther out in the canyon he'll be when he hits.

The coyote always fell the same distance from the canyon wall, no matter how fast he was going when he fell over. (Running or being pushed by a rocket up his *ss!) Explain that one!

The coyote always fell the same distance from the canyon wall, no matter how fast he was going when he fell over. (Running or being pushed by a rocket up his *ss!) Explain that one!

Now as I remember it, the coyote didn't fall until he bothered to look down and noticed he had waqlked off that cliff...if he hadn't of looked, he'd a just klept right on walking.

Want some bullets like that...guess I'm going to have to call Acme.

2) The nature of bullets is that they slow down out of the barrel, and thus drop.


What I meant here was the affects of the combination of the vector of forces on the bullet. Yup, gravity takes over as soon as it leaves the barrel. But its the velocity (well, momentim, energy, etc) that makes the drop happen over 50, 100, 200 yards.

Gravity isn't the only thing making the bullet drop...that is, not the only force working against the trajectory of the bullet. Just maybe the only one we can be sure of! :)

Anywho, this was all spurred by my comparison of 33 different .270 bullets/cartridges, looking at their velocities, energies and (very simple) trajectories. Of course, by using the manufacturer's #'s alone, I'm eliminating a ton of important variables. But...I've made some really nice charts and graphs!! ahahahah

cheers

jonas