5.56 vs .223

[Mydogmax]

Just curious. Is the 5.56 more accurate than .223 ammo at 100 yards or is it negiable. I realize the 5.56 is chambered at a higher pressure and the muzzle velocity is about 100 fps higher in the 5.56. Does it really matter? BTW. I'm shooting the M&P Sport.

 

[Engineer1911]

No

No is the direct answer.

But I'm just an apathetic rank amateur that doesn't worry about surgically clean brass, clean gleaming primer pockets, individually weighed powder charges, cartridge overall length controlled to ± 0.001" , or brass sorted by weight and headstamp. I have been doing it my way since 1975 and having a great time shooting rifles and handguns.

 

[m1gunner]

It is the quality of the ammo that makes it accurate. Top quality in either will deliver similar accuracy.

Milspec ammo accuracy in either loading will be about the same, and not as good as match grade ammo.

 

[GunarSailors]

In my humble opinion, the 5.56 ammo is more accurate than .223 ammo in a 5.56 chamber. The longer bullet gives more stability and more contact with the riflings than the shorter .223 bullet. Yours is probably chambered in 5.56

 

[JaPes]

Just curious. Is the 5.56 more accurate than .223 ammo at 100 yards or is it negiable. I realize the 5.56 is chambered at a higher pressure and the muzzle velocity is about 100 fps higher in the 5.56. Does it really matter? BTW. I'm shooting the M&P Sport.

Yes and no. There will be a shift in point of aim / point of impact. Is the difference something that can't be overcome with a touch of hold-over? No. That's the practical, on the range difference. I shoot both .223 Remington and 5.56 NATO from my 5.56 chambered rifles.

The internal ballistics of the 5.56 v.s. .223 chamber is the key to all of what you've been "hearing".

The difference between the performance of 5.56 and .223 is due to the 5.56 chamber with it's longer leade. The distance the projectile travels until it touches the rifling is the leade. In a 5.56, the leade is longer. This is one of the factors that allows higher pressure.

Fire .223 Remington from a .223 chamber, the lower pressure doesn't make a hill of beans difference because of the shorter leade. .223 Remington from a .223 chambered barrel should have more potential for accuracy than a 5.56 firing 5.56 NATO or .223 Remington.

A good read:

Internal Ballistics - Hornady Manufacturing, Inc

http://www.luckygunner.com/labs/5-56-vs-223/

 

[JaPes]

In my humble opinion, the 5.56 ammo is more accurate than .223 ammo in a 5.56 chamber. The longer bullet gives more stability and more contact with the riflings than the shorter .223 bullet. Yours is probably chambered in 5.56

The projectile weight makes the difference. The diameter of the projectiles is the same. To add weight to the projectile, the projectile gets longer. The shape tends to taper, becoming more aerodynamically efficient. The added projectile weight helps it to buck the wind.

Don't forget 5.56 M193 has a 55gr projectile. 5.56 M855 has a 62 grain projectile. The US used M193 in the 1970's. If I remember right, the 55gr projectile fragmented, tumbled, deformed on impact with human tissue and caused horrendous wounds. The heavier M855 62gr FMJBT was NATO's choice because the steel tip, heavier projectile was less likely to fragment. The enemy would still die, but die in a more humane way.

(How being shot and dying with an M855 v.s. a M193 is more or less humane is in my opinion a moot argument. Dying is dying. )

On a side note, the Russian 5.45x39 projectile has a FMJ with a hollow cavity inside. Guess what that round does on impact with a human? Projectiles deform, cavitation, more energy transfer into the tissue. It's more horrendous than getting a through and through with a 7.62x39 FMJ... but then again... getting shot and dying is still dying.

 

[WR Moore]

With any non-match grade AR, you're most unlikely to see any difference between .223 or 5.56mm in the 5.56mm chamber within 100 meters. This would be true even if the shooter was Olympic grade.

Given benchrest rifles (20 lb monsters with 2 oz triggers fired from machine rests) in the hands of experts in that sort of thing, you might see a difference. That difference wouldn't matter to the vast majority of shooters.

The difference in bore contact between 55 and 62 gr FMJBT bullets isn't significant.

The difference in terminal effect between the two is. As JaPes notes, the M193 tends to swap ends, break at the cannelure and fragment upon tissue impact. The steel insert of the M855 is due to a requirement to penetrate a specified protective helmet at X00 meters. As a result, M855 is much less disruptive of tissue.