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

"LONG RANGE TUNE.... Here is an interesting set of trajectory plots. No matter how carefully one loads his ammo, there are going to be small differences in muzzle velocity. Consider a load with an average muzzle velocity of 2915 fps with a muzzle velocity variation of 15 fps. Then consider this load tuned for zero vertical at 100 yards that overcomes that small difference in muzzle velocity.
This same load will be out of tune by 73.23-71.50=1.73 inches of vertical at 600 yards. However if the load is tuned so that there is 12.21-11.92=0.29 inches of vertical at 100 yards (with the slower muzzle velocity hitting higher) then there would be zero vertical at 600 yards. This chart is for a 6.5mm 140 gr VLD bullet with a 0.64 BC. A similar chart or table can be made for each long range load. If you are in tune for zero vertical at 100 yards, you will not be in tune for zero vertical at 600 or 1000 yards."

but but but....that can't happen....

...Jeff, I forgot to mention the other credible example of the phenomenon in your experiences. I'll hope that you consider taking Litz up on getting up to Michigan so he can try to figure out the "why" of the happening.

rcamuglia, that looks like Varmint Al's take on Positive Compensation.

Thanks jrh. I found it late last night on yarchives and posted it to LongRangeHunting, but didn't get a chance to post it here.

I've noticed a similar ballistic phenomenon numerous times.....

Most people tend to shoot their mouths off way better from long range, than they do up close and personal.

Another long range mystery...

Ever notice how awesome some chicks look at around 40-50 yards? But then look not that awesome up close?

This is referred to as the "40 Yard Fakeout".... It's been studied in depth for years.

Wrongo!!!

It's known as "Good from far, but far from good!"

You just need the right optics. Beer goggles work up close, and they work best in low light conditions.

I bet if there was a group of chicks at 100 yds, and Dogshooter starting walking toward them, that 100 yd. group size would shrink significantly due to dispersion....

This blew my mind. Way above my level of ballistics understanding!

I've seen non-linear dispersion on targets between close range and longer range. Nothing so drastic as 1 moa at 100 and the same at 200, but a load that shoots a consistent .7 moa at 100 and then .5 moa past 300. Could simply be shooter error, or other variables unaccounted for. Have only seen this with very long VLD-style bullets.

I don't think the linear dispersion model works with something spinning so fast, as that introduces an entirely different physics to the flight of the projectile in an atmosphere.

This thread reminds me of other physical 'impossibilities' that were later proved very possible, like a human running a 4-minute mile. There are many such examples. We as a race seem to have become very egotistical about what we 'know'.

If I could get past a few hurdles, I'd be tempted to take Litz's offer. Hoping someone does, because I do want to learn.

Laffin..... the prosecution rests your Honor.....

You're right though..... not too many folks at the SRM were envious of my .260.... same can't be said of my lady.

Where in Michigan is he?

You should be laffin', cuz it was funny

Gale did not write much on rec.guns ~~1997.
When he was in bed with cancer, he wrote on the modern www forum The High Road.

Clark,
I read your post before you edited it. I only know recguns from the yarchives, but Gale McMillans posts are very present there (as are BartB's.) Yes, I did frequent Shooters.com (mostly the Highpower board). There were some very cool discussions there (some of which like the pressure measurement discussion, I saved as pdf's and mht's). I'm not much of an optics guy but I do have a small collection of External adjust Unertl's, Remingtons, Lymans etc.
I think I remember you from the old Accurate Shooter site... ClarkM, engineer from the PNW?

There are a few ways that quantum mechanics could also play a part in explaining what is going on with non-linear dispersion. I keep wondering if that can somehow be experimented with. I know a lot of people prefer the Newtonian physics model, even though it has been surpassed in accuracy by the Quantum model.

LOL

Anybody know where in Michigan he is located?

Cedar Springs

http://appliedballisticsllc.com/about-us/

Bottom of the page....

David

This diagram can clear up a bunch of confusion, it was a test done a few years ago and helps qualify some misunderstood ballistic phenomenon...