Bullet drop balistics don't make sence - any ideas?

**MadRussian** · 07-04-2012, 01:00 PM

A few weeks ago I made this post:
http://www.northeastshooters.com/vbu...elp?highlight=

This is a follow up post with a more in-depth testing.
Here is the problem: when I reload for .223, keeping everything else the same and only changing the powder load - my hotter loads drop elevation faster then my lighter loads.
I'm using a 14.5 Daniel Defense 1/7 5.56 barrel, Hornady Z-Max 55gr bullets, WCC casings, and CCI primers with WC855 powder from the same bucket - basically keeping everything as consistent as possible.
The ammo was loaded with 21 through 25 gr of powder, the point-of-aim was the center dot in the cross hairs and this is what I got:
collective.jpg
21gr-1.jpg 22gr-1.jpg 23gr-1.jpg 24gr-1.jpg 25gr-1.jpg

What I can't quite explain is the 300m bullet impact with the 22gr bullets - either I shifted my point of aim and was shooting badly, or this just happens to be a good load for that barrel with a flatter trajectory. Otherwise you can see how the impacts are consistently shifting lower as the load gets hotter.

Any Ideas? Comments? Advice?

-Sergey

**bpm990d** · 07-04-2012, 01:44 PM

You have some good data and targets, but I'm curious about the methodology you used. Did you shoot 5, move back 100 yards, Shoot another 5, move back again and finish up? It looks counterintuitive and I'm at a loss except to say what is causing it, other than to guess that it may be some kind of barrel compensation. I know with all my rifles, lower powder charges hit the target lower.

Irregardless of where you aim, and where it hits, the highest velocity will be the flatest trajectory.

B

**terraformer** · 07-04-2012, 02:03 PM

In the older thread you got the most likely answer in posts #3 and #4. "Hotter" loads aren't always faster.

**gearjunky13** · 07-04-2012, 02:04 PM

Are you absolutly sure you dident mix up what you were shooting, im not implying anything just could have been a simple mistake. i dont know much about reloading my self but i do know once its put back together its hard to tell what you got in each one if you did not mark it.

**xtry51** · 07-04-2012, 02:12 PM

WAG, but what kind of optic are you using? Is it shifting zero?

Also did you chrono the rounds? If so what were the velocity avg and max-min?

What ammo and range is your gun zeroed at? What is the velocity of the ammo used to create original zero?

**gearjunky13** · 07-04-2012, 02:13 PM

Just a thought, but is it possible that with more powder your not getting as fast of a burn out of it, kinda like its not burning as fast because with more powder taking up room in the casing maybe less gun powder is exsposed to the ignition source, or is possible you need a longer barrel to utilize the extra expansion of gases, kinda like the built has left the barrel before the full push of the powder load could get it up to its full potental velocity of that load.

Im no exspert on gun powder or reloading so im just making sugestions so feel free to correct me im all for it

**xtry51** · 07-04-2012, 02:13 PM

Originally Posted by gearjunky13

Are you absolutly sure you dident mix up what you were shooting, im not implying anything just could have been a simple mistake. i dont know much about reloading my self but i do know once its put back together its hard to tell what you got in each one if you did not mark it.

Side note on this. Personally I mark batches with different color sharpies and put them in individually marked boxes. No chance at a mix up.

**gearjunky13** · 07-04-2012, 02:31 PM

Originally Posted by xtry51

Side note on this. Personally I mark batches with different color sharpies and put them in individually marked boxes. No chance at a mix up.

I figured that much but wanted to verify.

On a side note you have forced me to learn more about gun powder today, i will have to fix my earlier post now.

**MisterHappy** · 07-04-2012, 05:52 PM

Physics is physics.

With ballistics, other factors come into play.

Internal ballistics...different burn rates, different loadings different results.

External ballistics....different weights and designs of bullets will retain velocity differently.

Don't sweat the theory - make up a load that you and your gun likes.

**economist** · 07-04-2012, 06:09 PM

Of the five loads, your velocity appears to be maxed out for the 22gr load at 300 yards. So, either that was the load with the most powder (labeling error) or the loads with more powder are resulting in something that is causing velocity to fall relative to that 22gr load.

Bullet drop balistics don't make sence - any ideas?

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