Home Forums Hunting & Shooting Long Range Hunting Smaller dispersion at longer range than at close range.

Doesn't that describe the way those making the claim shoot their groups?

I don't know why you would think that scenario has even a remote resemblence to several people watching someone shoot, and then verifying the results by viewing the targets

The trajectories intersect because you're using a 325 yard zero in your ballistics calculator, and the calculation adjusts angle of departure to line up with that zero, regardless of the velocity or other parameters.

Try the same thing but use a near zero (like 50 yards) instead of the far zero, the results will be quite different, and more accurate (although still not perfect).

Yon--good post.

Snyper,

Yes, I believe in the cases I've heard about, velocity spread was likely (ex-military ammo or ready rolled of less than best consistency). The article I posted mentions it.

We don't have expert witnesses otherwise this issue would have been solved some time ago. I believe we have people making assumptions based on observations, myself included. Human nature to fill in the blanks of understanding.


Yondering,

The base load of 2800fps is zeroed at 100yards. I adjusted the departure angle to give +/- half an inch at 100yards (overall "group" or dispersion of 1MOA) for the 2700 and 2900 loads. They don't all exactly intersect at 325yards - I was suprised how close they came with my rough assumptions and calcs (one intersection at 310yds, another at 340yds and the last at 370yds):

http://i795.photobucket.com/albums/yy237/mauserand9mmagain/trajectories/250to400_zpsd6bdd5ba.jpg

I went back in this thread and discovered the following:

rcamuglia already mentioned the effects of velocity on trajectory and departure angles on page 3 (as I rediscovered for myself)

ChrisF included exerpts from a publication for the same on page 5

BryanLitz mentioned the existance of bullet spiralling on page 7, and that is extremely minor (0.1 x caliber).

We dont need "expert witnesses"

All we need is for one or more of those who say they own these "magic rifles" to fire them with witnesses that can say they saw them fire smaller groups at long range than the gun could fire at close range.

Then they can let someone else run the same test with the same rifle to make sure it wasn't flawed

This doesn't require a lot of calculations and charts

It requires simple proof by doing it in front of a crowd

And yet not one has taken the opportunity to prove it to the world

And no one will

I believe the velocity difference is what is causing the increase in MOA accuracy (but only at a specific range and then MOA accuracy increases again as the range increases).

And I'm actually with you on this, if someone says they use consistent loads and experience an increase in MOA accuracy at any range, then I really doubt this is true, and, like you said, they'll never be able to prove it.

Compensating barrel vibrations will only increase accuracy, with the normal drop-off as the range increases. The key is you need velocity variation to cause the trajectories to cross over and get the reducing MOA accuracy effect (but only at a specific distance).

It was an interesting myth to explore, but it's gone the way of bigfoot and the Loch Ness monster. Technology and science always kill off the unusual.

Edit: And I should add to those that claim to have witnessed consistent increasing MOA, I'm not calling you liers, just misinterpreting the observations. Like I've tried to imply earlier, if we are not prepared, we are poor witnesses. Nothing shameful about that.

OK, that makes more sense, thanks.

If you include the [IMG/] codes in your image links, the pictures show up without having to click a link. (That's what I did in my post above with your link.) Photobucket does that for you if you use the IMG link.

Found this:

https://www.youtube.com/watch?v=C9Dylxy3zJc

Mutilated projectiles with spiralling and erratic trajectories.