Sunday, August 26, 2012

Effective Range of Your 223 or 5.56 Rifle

After having several discussions with friends I did some research on the effective range of AR-15 rifles using various types of ammunition.  In this post I'm going to discuss the maximum effective range of the most common bullet weight and type, 55gr full metal jacket (FMJ).  As many people know the standard 55gr full metal jacket projectile's primary wounding capability comes from fragmentation.  There is wounding performed by hydrostatic shock as well, and of course the path of the bullet.  If a bullet itself hits a major blood vessel or vital organ it can of course be lethal.  But when a bullet expands or fragments it greatly increases both the wound channel and the potential to damage something vital.  It's a morbid topic, but if you use a firearm for hunting or defense, you want it to be effective, so it's an important discussion.

If a person chooses 55gr .223 or 5.56 NATO ammo for use in a defensive carbine it's important to fully understand the fragmentation qualities and understand what the maximum distance is at which a bullet fired from your rifle will still possess fragmentation qualities.  This is because it takes a fair bit of velocity to give the bullet enough energy to fragment when it strikes a target.  Most experts suggest the necessary velocity to ensure reliable fragmentation is 2700 fps.  I've chosen this bullet for this discussion because by a large amount it's the most common bullet found in .223 and 5.56 ammo.

Barrel length is correlative to muzzle velocity.  The shorter the barrel, the lower the muzzle velocity.  The shortest barrel seen in 5.56 rifles is 7", which is pretty stupid honestly.  A large percentage of the powder burns outside of the barrel and the velocity is way down when compared against a standard length carbine.  For purposes of this blog, we'll be starting at a barrel length of 10.5", a popular length for short barrel rifles used by military, police and civilians.

A M193 (the military standard 55gr 5.56 cartridge) generates a velocity around 2750 fps in a 10.5" barrel AR-15.  This isn't much higher than the fragmentation velocity.  Since the bullet will be losing speed every moment after it leaves the barrel, we can figure out it's going to drop below the magic velocity threshold around 20 meters.  That's not much of a range at all.  If you are using a 10.5" rifle for defensive use, you'd likely be better off with a different type of bullet.

As an aside, I'm using nice round numbers here, if you want to know exact ranges you'll have to know your exact velocity out of your rifle.  It could easily be 50 fps plus or minus the average velocities listed here which will change the range by a meter or ten.

If we move up to an 11.5" barrel we pick up a bit more velocity, 2875 fps or so.  It's a pretty nice bump from 10.5".  It shows how a cartridge and the burn rate of the powder chosen for factory loadings in that cartridge is tuned to a specific barrel length.  So by moving from a 10.5" to a 11.5" barrel we extend our fragmentation range out to 50 meters.  This is a more useful range, but still very limited.

12.5" gets us to 2950 fps.  This brings the range to 75 meters, still very limited.

14.5" gets us 3050.  This is the barrel length used by the military in the newest version of the M-16 rifle which is commonly called the M4.  The velocity increases are slowing down at this point, most of the powder has burned by the time the bullet exits the barrel.  This takes our effective frag range to 100 meters.  This is becoming more practical for an effective defensive range.

16", the most common barrel length sold in AR-15 carbines and the shortest length available for general sale, gives us a muzzle velocity of of 3125. Fragmentation range extends out to just over 100 meters, not much longer than the 14.5" barrel.

The second most common barrel length for AR-15 rifles is 20".  The M193 round gets 3250 fps and a range of right around 150 meters.  This gives us a 50% increase in effective range over the 16" barrel.

24" gives us 3300 fps, barely any more velocity than than the 20" barrel.  We've passed the sweet spot for this particular cartridge, where additional barrel length gives us lower velocity increases.  16 to 20 inches is really the ideal barrel length for this cartridge.  A 24" barrel gives us very little fragmentation distance over a 20" barrel.

All of these calculations were done around the military spec M193 5.56 NATO cartridge.  If instead you use .223 Winchester ammo offered by Winchester, Remington, PMC or other companies, your velocity could be 100 fps lower than M193, as .223 is loaded to a lower pressure than 5.56 NATO.  If you are using Wolf, Brown Bear or Silver Bear .223 ammo, your velocities could be 150 fps slower.  That can reduce effective fragmentation ranges effectively.  Using steel cased Wolf .223 ammo in a 11.5" short barrel rifle gives almost no fragmentation capability.

In no means is this an attempt to talk people out of using 55gr ball ammunition for defense.  It is an ideal cartridge for defensive work, especially in residential areas where light obstacles (like interior walls) will cause it to fragment very quickly and reduce the chance of missed shots striking or hurting unintended targets.  But if it is the ammo you chose to use, you should understand it's capability.  Once you extend past it's fragmentation range, you are likely better off using another ammunition type.  For instance, the 55gr TSX bullet made by Barnes should offer reliable expansion down to 1,800 fps.  This extends the range quite a bit at which it offers good terminal ballistics.  A reasonable person could practice with 55gr FMJ ammo and use the TSX bullet for hunting or defense to extend your effective range.

Fortunately, there are scores of options for 5.56 and .223 ammunition, with many bullet types designed for different purposes.  Some bullets are designed for varmints and offer very fast expansion, some for medium game and expand and retain weight and offer deep penetration.  Choose your ammunition wisely for your purpose.

If you'd like to see ballistic gelatin testing of various .223 and 5.56 rounds, you can review them in this pdf from ATK

18 comments:

  1. This is a good range as I have shotgun and its range is just 40 yards but I think this rifle's range would be higher than it and also more accurate.
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  2. This post wasn't discussing the effective accurate range of rifles with various length barrels, it was discussing the maximum range at which one could expect the most common bullet type sold in this caliber to fragment. I thought that was pretty clear. The maximum range of these rifles is much farther and dependent on manner factors not mentioned here.

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  3. I wouldn't depend on fragmentation at all for self defense. Look up fleet yaw and AOA variations and you may find that you can never trust FMJ to fragment. Even if it fragments at 20 meters, it may not at 19.5 or 20.5. I'd second your excellent recommendation for the copper projectiles.

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  4. Accuracy doesn't matter for if you are using shotguns. But the distance the shotgun shells cover are comparatively shorter than the bullets of rifle. Thank you for this informative article. Keep writing, Pete.

    Regards,
    Jacky
    MA Firearms School

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  5. As others have said, I wouldn't rely on FMJ to fragment nearly at all. If you want to look at fragmentation capabilities, look at hollow points and soft points. FMJ is meant to go far to penetrate and pierce targets (if lead core it won't pierce steel armor usually, but if XM855 steel core it becomes MUCH more effective to pierce targets and light armor).

    If you are buying 55gr ammo, I would suggest getting .223 so you'll never be in a situation where you give someone with a .223, 5.56 ammo and it could be dangerous.

    As for higher loads, 62Gr steel core is an excellent round. I am limited to a 16" 1:9 twist barrel, so I target shoot with .223. To minimize ballistic differences, my second choice of ammunition is 60 Gr Soft point, an effective hunting round and self-defense round.

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  6. A couple things i noticed, 1. .223 winchester? did you mean to say .223 Remington? 2. Fragmentation of FMJ Nato rounds does happen below 2700fps, with 2500fps being the cut off, however with the decreasing velocity, the amount/level of fragmentation decreases as well. Putting the bullet in the right spot is more important than its fragmenting capabilities, IMO. Though it is nice to have the devastating capability that fragmentation gives. If yer not in a organized military establishment, you have a lot of other, effective bullet style options available to use for... whatever situation that develops. Something to think about... ANY hit is an effective hit, some hits are more effective than others. If your enemy is bleeding their life onto the ground... you are winning.

    Jake, Buy 5.56 if you can, .223 only if you cant buy 5.56. Why would you buy lesser powered ammo for others poor choices? I have a list, Will you buy some ammo for me also? lol. Too bad for others if they dont have compatible weapons.

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  7. Hey There. I found your blog using msn. This is a very well written article. I’ll be sure to bookmark it and come back to read more of your useful info. Thanks for the post. I’ll definitely return.
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  8. Thanks for the post, people can also take help form the MA Gun License to know about the guns and firearms with proper training and licensing. They can also let you know what about these bullets and which guns are for them.

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  9. Like it was said before, FMJ rounds are for penetration, and that is why the military uses them. While it is possible that the round may ricochet off bones, that is dependent upon the weight of the round, and the energy left propelling the round. Liberty Civil Defense rounds are monolithic copper rounds that are designed to fragment violently after entering a wet substance. FMJ's are designed to defeat light body armor/thick clothing at farther ranges. Also, FMJ's are known to feed well, whereas different types of hollow points may not. FMJ ammo is also cheaper, and I think that is why the government uses it. I believe they feel it is 'good enough' for their intended use.
    But to reiterate what has already been said:
    1. Don't base your ammo selection on tumbling because it cannot be counted on.
    2. Buy ammo intended for the purpose you are using it.
    3. Piercing a vital organ with a FMJ is far more effective than missing with a hollow point.

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  10. This article makes me want to stop using SBRs as defense tools, I love my AR pistol w 8in barrel, its super portable and very accurate at 25-50 yards. However its disheartening to read that it loses any fragmentation after 25 yards.

    Will it still possess enough velocity to penetrate a soft target such as deer or coyote at 50+ yards? What about walls, body armour, car doors, etc.

    Guess I need to get some watermelons and some scrap car parts and see what she will do at 50+ yards.

    I feel like I want to stop thinking of the .223 SBR as a defense weapon after reading this, and either go with 7.62 in the next build.

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  11. Very easy to read and digest article...well written. Thanks a lot!
    can you do similar analysis to a .308 caliber? I would like to understand at what barrel length do I start getting diminishing (or plateauing) return?

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  12. Ummm... you guys do know that around 1900 there was a professional hunter who went after elephants with a .22lr - just to prove it could be done. He was a good shot and knew where to put his rounds, but he had no problem killing bull elephants with that rifle. Lets put it another way - walk out 400 yards - let me shoot you with a 16" barrel AR15 with 55 grain m193 - then walk back here and tell the rest of us how you feel. You say: "that's not the point". No that is exactly the point - a .22lr will kill you deader than a doorknob, and a 5.56 NATO round is more powerful than a .22 out to very long range. Infantrymen in Vietnam killed tigers with their M16s and M193.

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  13. Great Article is this and I like it very much.IdealShape coupon

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  14. This comment has been removed by the author.

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  15. 223. is more than enough going Mach 3 the speed of sound. A 22lr 40gr kills more Americans dead than any military 223. round has. Unless your going to battle the Police no need to deploy a 223. on a civilian.

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