.223 question after range session

[GI_Jared]

Just started reloading .223 and have one question after a test session at the range. I tested two loads, one 55gr and one 68gr. What I found odd is that my rounds fired with the 55gr were dead on windage wise, but the 68gr loads where 3 inches to the left of my point of aim. I am thinking that the powder may not be ideal for heavier grain bullets, but i really don't get why that would affect the windage. Any thoughts???

16" 1/8 Twist stainless wylde chamber at 100 yards

68gr Hornady HPBT
23.5 gr of H322
2.25 OAL

55gr HPFB Midway Dogtown
23.9 gr of H322
2.25 OAL

First rounds, 68gr HPBT


Second, 55gr HPFB


Third, 55hr HPFB

 

[LivewireBlanco]

My guess would be barrel harmonics. I had the same thing happen with my M1 Garand with 150 vs 165 grain bullets. I wouldn't worry about it other than sight in with the ammo you're goibg to shoot.

 

[ArchAngelCD]

I'm going to take a wild and offbeat guess. Was there a crosswind blowing? My guess is, the wind was blowing from left to right but not hard enough to effect the heavy bullet that hit to the left but the wind was hard enough to push the lighter bullets to the center of the target. (I told you it was a wild guess) Is this at all possible? I think my guess would be more possible @200 yards instead of 100 yards but that would depend upon how hard the wind was blowing. (if it was wind) I have not heard of a powder causing one weight bullet to hit left or right of another.

 

[MtnCreek]

Parallax? Too much coffee?

 

[dodge]

Generally when you different bullet weights they will hit the target at different points of impacts. This is just the nature of the beast. With my 243 using Sierra 85 gr HPBT I'm dead on at 100 yards but if I use the Sierra 100 gr spritzer they will hit 1"- 1 1/2" higher and about 1/2" to the left of my setting that I use for the 85 gr. All you need is to find the most accurate load for your rifle and sight it in with that load. If you want to experiment with different loads just go ahead but remembering that they will have different points of impact from you go to load.

 

[au_prospector]

I am told velocity has an effect on windage. I found this out by loading .45-70 350 grain bullets. One set was loaded with 40 grains of IMR 3031 and shot left about 3 inches POA at 50 yards. Another set was loaded with 43 grains IMR 3031 and shot right on POA at 50 yards. I asked an old timer at my range if he had ever seen this effect and he simply said, "Velocity has an effect on windage."

 

[Regular Joe]

Bearing surface is a big factor. Look at the section of the bullet that is engaged by the rifling, and notice that it's much longer on the 68 gr. bullet.
Also, there are more differences in the configuration of the bullet than may be apparent. The 68 gr. match bullet has a bit of "dead" space between the front of the lead core and the inside surface of the jacket at the nose.
If you have a LOT of each load, it could be worth making a not of the correction between them for a 100 yard zero.

 

[hentown]

Anybody hazard a guess at how much wind it would take to blow a 68 grain bullet three inches @ 100 yds? I'm guessing around 80 mph.

 

[gamestalker]

I've experienced the same thing even with bullets of the same weight, but different brand. But I also had it happen when I went from a 120 gr. down to a 110 gr. in 7mm RM and other high powered cartridges.

I zeroed the 120's at 100 yds. and 200 yds., dead on with just an elevation compensation being the only adjustment necessary. And then when I fired the 110's they were grouping very nicely, but all were about 5" high and about 2' to the right @ 100 yds. and also high and right @ 200 yds.. No wind to speak of.

Having seen this happen with various rifles and bullets over the years, I have chalked it up to barrel harmonics. Every firearm and bullet has it's own personality.

GS

 

[stavman11]

I have the same Challenge with some different lead as well

my 55gr HP's will hit dead on at 100yds..
the 55gr FMJ-BT will hit High about 3" and left about 2"

I have assumed the Parachute ability of the Hollow points create an additional Coaficancy and increased the Accuracy and they DROP onto Target with deadly Aim
Now the FMJ do not have the Parachute factor to Increase the Accuracy so they FLY down range with Reckless Abandon ready to Tear up anything in their Path

In all seriousness.... it has stumped me as well. the Z-max, V-Max all perform Similarly as the HP's but those Darn FMJ's just dont Cooperate

I agree its the velocity and Harmonicks that effect the Bullet...

So I keep the FMJ for my Close Range AR... and the others for Punching Holes in paper

 

[ArchAngelCD]

Anybody hazard a guess at how much wind it would take to blow a 68 grain bullet three inches @ 100 yds? I'm guessing around 80 mph.

THAT'S NOT WHAT I SAID! I said the wind "might" have blown the 55gr bullet over and the 68gr bullet was the real POI. Please read what I said carefully before you try to make me look foolish with your wink!

 

[Otto]

The wind didn't blow the bullets to the center of the target...that's ridiculous.
If you refuse to believe that, here's a calculator. http://www.handloads.org/calc/index.html

 

[hentown]

THAT'S NOT WHAT I SAID! I said the wind "might" have blown the 55gr bullet over and the 68gr bullet was the real POI. Please read what I said carefully before you try to make me look foolish with your wink!

Your absolutely right! Let me rephrase: Anybody hazard a guess at how much wind it would take to blow a 55gr bullet 3" @ 100 yds? I'd guess about 80 mph! (Better?)

 

[Jim Watson]

Everybody knows that barrels with twisting grooves shoot better because the spin slings off the demons released when the brimstone in the gunpowder burns.
But the bigger bullet gave the demons more to hang on to, so they stayed with it and steered it away from the bullseye to confound the shooter.
The smaller bullet spun off its demons so it went straight.

 

[AABEN]

Just started reloading .223 and have one question after a test session at the range. I tested two loads, one 55gr and one 68gr. What I found odd is that my rounds fired with the 55gr were dead on windage wise, but the 68gr loads where 3 inches to the left of my point of aim. I am thinking that the powder may not be ideal for heavier grain bullets, but i really don't get why that would affect the windage. Any thoughts???

16" 1/8 Twist stainless wylde chamber at 100 yards

68gr Hornady HPBT
23.5 gr of H322
2.25 OAL

55gr HPFB Midway Dogtown
23.9 gr of H322
2.25 OAL

First rounds, 68gr HPBT


Second, 55gr HPFB


Third, 55hr HPFB

What is the make of your bullets" some flat and some bolt tail? That will make a different. Jack the speed up on your 68gr bullets and see if that will help.

 

[SWThomas]

It would take hurricane force winds to get wind drift with a 223 at 100 yards.

 

[Ifishsum]

Due to barrel harmonics (and other factors), different bullets just hit different POIs. Could be horizontal, vertical or both. Even the same weight bullet in a slightly different style may do that. It doesn't mean anything to me, as long as they group well. Once you settle on a load, just adjust your optics or sights to its POA.