Barrel Length Studies in 5.56mm NATO Weapons

8 ball said:
With all due respect, how does muzzle velocity affect accuracy? I have a number of short barreled rifles ( 7.5-10.5 inches) and they will shoot 1-1.5 inch groups at 100 yds with loads that they like. Not bench rest quality of course, but certainly very comparable to the same loads in a longer same quality barrel.
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Virtually nothing. The longer barrel may be a slight advantage in one area. Since the bullet is travelling faster, the wind has less time to push it. I think that's splitting hairs though.

A lot of people who know much more than I do, say shorter barrels are more accurate. See the link below:

http://www.6mmbr.com/barrelfaq.html#24642
 
smak_daddy said:
I wouldn't shrug off a .22 LR hit. Being shot with a 22 LR is extremely fatal if it hits you in the right place. Even out to 200 yards.

Shot placement trumps calibre almost every single time.
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That's why police and military use .22 LR exclusively.Laugh2
 
Broker said:
That's why police and military use .22 LR exclusively.Laugh2
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So if someone offered you this deal: "You shoot me in the foot with a 308 and I will put a 22lr behind your ear. Whoever is alive in 10 minutes gets a million dollars." You would take it? Shot placement will always be the most important factor. When shot placement is equal then you can start talking about calibers, velocity, bullet types etc.
 
yeah, civies dont have the hauge conventions, so any heavy hollow point expanding bullet will over come the lack of dependable fragmentation on ball ammo at sub 2700fps.

of course a HP bullet at 2700 is still better then one at 2500, but both will do the trick
 
7.6X39 in short barrels

From M4Carbine.net Forum
http://www.m4carbine.net/showthread.php?t=65613


762x39Velocities1.png


We down loaded some of the 7.62x39 DPX loads to 1800 fps to check this out. We still got perfect expansion with penetration of 18" in 4 layer denim clad 10% ballistic gelatin.
__________________
Michael Shovel
Sales Manager
COR-BON/Glaser
Mike@CORBON.com
Wow, great performance with the 7.62X39 round!

From: http://ammo.ar15.com/project/Self_Defense_Ammo_FAQ/index.htm#.223
Assault Rifle Comparison

40052-MilitaryAssaultRifleWPcopy.jpg
 
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newshot said:
So if someone offered you this deal: "You shoot me in the foot with a 308 and I will put a 22lr behind your ear. Whoever is alive in 10 minutes gets a million dollars." You would take it? Shot placement will always be the most important factor. When shot placement is equal then you can start talking about calibers, velocity, bullet types etc.
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You are absolutely right.

However in discussing terminal ballistics we assume the shooter can hit the target. It is what happens after the bullet hits the target that concerns us.

A better example is:

A person is shooting at you from 200 yards away.
You have a 10.5 inch AR and two different magazines.
One contains cartridges that have been proven, through testing, to do massive internal damage when a center mass hit on a person occurs at that range.
The other has been proven to do minimal damage as it simply passes through the body.

Which magazine would you load your AR with?
 
Deer Hunting Cartridge Recommendation from the Federal Premium Website

noslerPartition_big.jpg

Load No: P223Q


Muzzle Velocity: 3160 fps
Bullet Style: Nosler® Partition®
Bullet Weight: 60 grains 3.89 grams

I would suspect something like this would make a great civilian defensive cartridge in a short barreled rifle as it does not depend on break up or tumbling to be effective.

What do you think?
 
Broker said:
You are absolutely right.

However in discussing terminal ballistics we assume the shooter can hit the target. It is what happens after the bullet hits the target that concerns us.

A better example is:

A person is shooting at you from 200 yards away.
You have a 10.5 inch AR and two different magazines.
One contains cartridges that have been proven, through testing, to do massive internal damage when a center mass hit on a person occurs at that range.
The other has been proven to do minimal damage as it simply passes through the body.

Which magazine would you load your AR with?
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I guess the weaker one since in that scenario I am the one being shot at :). I think everyone agrees on the basics, I was just agreeing with the other poster that a 22 is not a harmless bb.
 
Excellent terminal ballistic videos from ATK (Federal and Speer)

http://le.atk.com/general/irl/videos.aspx

What do you think?
 
This Thread should be made a sticky!!!! There aren't enough people out there that understand the limitations of short barreled 5.56 firearms.

I have read a lot of info about this online. The issue is very deep, and when you go deep enough you get down to the fact that 5.56 is f**king retarded, and should have never been adopted by NATO. But that's besides the point.

There is no doubt that punching holes in paper remains more than possible at extended ranges with a shorter barrel. However, with the studies done, fragmentation is everything, there is also no doubt that anyone with intent on engaging human targets with 5.56 at an average of 100M or greater, should be at bare minimum using 14.5" barrel, even that is pushing it. Personally unless I was getting in and out of a vehicle constantly, I would not be caught dead with anything less than 16" and ideally I want 20" of barrel to get the most out of 5.56.

As far as these 8", 9", and 10.5" packages, they are completely in-effective outside of 100M even with the new heavier rounds. Now that doesn't mean there not useful, if your in and out of a vehicle, and constantly on the defensive, like a lot of PMC, and Security type jobs, then all you'll ever need is that short range defensive weapon.

It's a tool box, there is no one rifle, or one barrel length to rule them all, I wish it were so, you just have to adapt the weapon to the role.

Also to all of those suggesting hollow point ammunition. There is more than one reason that the military doesn't use HP ammo. It doesn't function well in full-auto weapons because of how hot things get. Especially in a DI AR. You would have the same effect if you got a Semi-auto into a sustained fire fight, they weapon components get too hot, and deform the bullet tips, causing all kinds of issues. That's one reason why it works for hunting but not for a sustained (HOT) fire fight.....
 
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Great thread, I only really started realizing the relationship between bullet design, barrel length and fragmentation a few months ago and most of the info I found is in this thread. It's why I keep a couple mags of 75gr TAP with the rifle, and save the M855 for the range:

SAMMI_pressure_Hornady_75_gel_shot_from_16_inch_barrel.jpg


Here's a picture of some recovered M193 (afaik)...a good illustration of the problem at hand:

http://3.bp.########.com/_WlAfoA27tZc/TLOOrZ_wBWI/AAAAAAAAAXY/FWcfU6kk5Dw/s1600/fragmentacion+5,56x45+mm+NATO+.jpg


I highly recommend everyone interested in this topic to read this entire page...again, lots of repeat info, but it's pretty comprehensive:

http://ammo.ar15.com/project/Self_Defense_Ammo_FAQ/index.htm
 
One thing that I think should be clear is the value of 2500 fps.

This is when the entry velocity into tissue can cause the tissue to expand beyond it's elastic limits and you end up with the tearing as shown in Dr Facklers wound profile. This does not mean that the bullet is useless.....it means that there is added benefit when the bullet is going over 2500 FPS when it enters tissue.

As with ALL wound ballistics - shot placement is EVERYTHING. The bullet then needs to get to tissues deep ehough to damage them.

Boltgun
 
Speer Gold Dot: 10 inch barrel to 200 yards

It's interesting that this is a Soft Point Cartridge and that they claim it will be effective from a 10 inch barrel at up to 200 yards.
The Federal Premium LE cartridge is also a bonded soft point. As per the video, it appears a soft point is the way to go, not a JHP or FMJ.
What do you think?

From their web page: http://le.atk.com/general/speerproducts/rifle/default.aspx

Speer® LE Gold Dot® Duty Rifle Ammunition

SPEER LE® Gold Dot® Duty Rifle brings proven bullet technology to rifle platform. The Gold Dot® bullet was the first high performance, bonded-core bullet available in handgun ammunition, and has since set the bar for duty ammunition. The nation's number one law enforcement option is now available in rifle ammunition for agencies everywhere. These specially designed loads bring law enforcement rifle ammunition to the next level.

Gold Dot rifle bullets are optimized to ensure expansion out of barrels down to 10" at a wide variety of velocities out to 200 yards. This kind of performance greatly increases the capabilities of duty rifles and gives law enforcement personnel a distinct advantage when it matters most. In addition, these new loads boast outstanding feeding in short, very short and standard length AR platforms.

Like their handgun counterparts, the Gold Dot rifle bullets are constructed using Gold Dot technology. The process of joining the jacket and core one molecule at a time eliminates the potential for the leading cause of bullet failure—jacket/core separation. It also ensures impressive weight retention through barriers as tough as auto-glass.

In addition to being tough, Gold Dot rifle loads boast outstanding accuracy. Exact tolerances and unprecedented bullet uniformity of jacket thickness give Gold Dot rifle loads outstanding accuracy. In addition, these loads feature flash suppressed propellants and a muzzle velocity of up to 3000 fps.

The versatility, reliability and superior construction of the new Speer LE Gold Dot Duty Rifle loads allow law enforcement agencies to utilize this tested and proven bullet technology in duty rifles with complete confidence.
 
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Recce21 said:
This thread is awesome. I love diving down the rabbit hole regarding ballistics. Terminal, Intermediate, etc etc. Love it.
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Or you can use what has proven to work: Mk262 ammo like US special forces do.
This ammo uses a 77gr cannelured Sierra Match King with a much better BC than M855 63gr bullet and a heavier bullet means lower loss in muzzle velocity in shorter barrels, the result: 300m effective range but lower barrier penetration.

Any 223 Rem/5.56 NATO cartridge still is a 250m varmint cartridge but it can be made to work in shorter barrel if you consider OTM (match hollow point bullets) legal for warfare and don't care about barrier penetration.

Alex
 
Interesting article on the mk262 from:
http://archives.gunsandammo.com/content/black-hills-mk-262-mod-1

Using an 18 inch barreled sniper rifle:
"Yet the ensuing firefight did not go as the Iraqis had planned. Rather than being overwhelmed, the three Americans instead put down a hail of highly accurate rifle fire. Advancing against this murderous wall, entire sections of Iraqi infantry were simply cut down. Screaming and rattling away with their Kalashnikovs on full auto, they were knocked from their feet by carefully aimed shots. When staggering losses finally broke their spirit, the surviving Iraqis either threw down their weapons or simply ran away. Scattered about lay the bodies of 167 of their comrades. The Iraqi dead lay in mute testimony to the Americans' tenacity and marksmanship skill.

With the criticism of poor terminal performance leveled by many on the 5.56x45, you would think those 167 Iraqis were cut down by 7.62mm M14s. Such was not the case. They fell to 5.56 Mk 12 sniper rifles firing 77-grain Mk 262 Open Tip Match ammunition. Developed to offer increased accuracy, range and improved terminal performance over the standard 62-grain M855 load, the Mk 262 has performed quite well in actual combat. "
SPRCrane.jpg

Mk 12 Special Purpose Rifle
 
Broker said:
Interesting article on the mk262 from:
http://archives.gunsandammo.com/content/black-hills-mk-262-mod-1

Using an 18 inch barreled sniper rifle:
"Yet the ensuing firefight did not go as the Iraqis had planned. Rather than being overwhelmed, the three Americans instead put down a hail of highly accurate rifle fire. Advancing against this murderous wall, entire sections of Iraqi infantry were simply cut down. Screaming and rattling away with their Kalashnikovs on full auto, they were knocked from their feet by carefully aimed shots. When staggering losses finally broke their spirit, the surviving Iraqis either threw down their weapons or simply ran away. Scattered about lay the bodies of 167 of their comrades. The Iraqi dead lay in mute testimony to the Americans' tenacity and marksmanship skill.

With the criticism of poor terminal performance leveled by many on the 5.56x45, you would think those 167 Iraqis were cut down by 7.62mm M14s. Such was not the case. They fell to 5.56 Mk 12 sniper rifles firing 77-grain Mk 262 Open Tip Match ammunition. Developed to offer increased accuracy, range and improved terminal performance over the standard 62-grain M855 load, the Mk 262 has performed quite well in actual combat. "
SPRCrane.jpg

Mk 12 Special Purpose Rifle
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Thanks for posting that, a good read.
 
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