Barrel Length Studies in 5.56mm NATO Weapons

[Broker]

Maximum effective frag range using CF ammo

From: http://forums.army.ca/forums/index.php?topic=35229.0

With C77 ball

You're looking at a fragmentation range of:
5-10m with a 10" C8CQB
45m with a 14.5" C8/C8A1
90m with a 16" C8SFW / C8FTHB
130M with a 20" C7/A1/

_____________________________
M193 impact velocity in human tissue for reliable fragmentation 2700 fps

M855 = 2600 fps

Mk262 = 2200 fps.


Kevin S. Boland
Director of Military Operations
Knight's Armament Company
701 Columbia Blvd.
Titusville, Fl 32780
1(321)607-9956
______________________________
From: http://www.gd-otscanada.com/html/en/products/detail.php?id=1&thisSection=77

C77 Ball
Small Calibre
Cartridges 5.56 mm

Ball C77

The NATO qualified 5.56 X 45 mm Ball cartridge. It is equivalent to the SS109 and M855 cartridges. Its projectile comprises a hardened steel penetrator and lead core in a gilding metal jacket. The maximum chamber pressure is well below the maximum NATO limit, ensuring that the ammunition in safe to use. The C77 cartridge functions properly in all NATO nominated weapons.

Nominal Muzzle Velocity : 910 m/s
Nominal Bullet Weight : 4 g. (62 grains)
Muzzle Energy : 1,500 joules (minimum)
Accuracy: 20 cm maximum standard deviation at 550 m.
Penetration
1020 steel plate (Hardness = 50/70 Rb; thickness = 3 mm) at 570 m

 

[Broker]

Hornady Urban TAP 60 grain

The Hornady® 223 Rem 60 gr. TAP Urban® offers high velocity in 14.5" or longer barreled weapons. It is the lightest grain weight that Hornady® recommends for 14.5" barreled firearms with NATO chambers, and the heaviest weight acceptable for 1-12" twist weapons. The 60 gr. bullet offers performance similar to that of other polymer tipped Hornady® 223 bullets, but with slightly higher retained weight and deeper, more consistent penetration. This bullet’s barrier performance is very similar to that of the 55 grain TAP Urban®, but slightly enhanced.

Intended for use in a 1-7"-1-12" twist barrel.
Performs optimally in a 1-9"-1-12" twist.

*All 223 ballistics gelatin shots were taken from 30 feet.*

From:
http://www.hornadyle.com/products/more_detail5039.html?id=130&sID=73&pID=3

Interesting that Hornady recommends 60 grains as the lightest grain weight that Hornady® recommends for 14.5" barreled firearms with NATO chambers, and the heaviest weight acceptable for 1-12" twist weapons.

What do you think?

 

[Broker]

Hornady 5.56 NATO 75 gr. BTHP T2 TAP®

Specially designed profile optimizes function and feeding in M16/M4 variant guns.

The T2 bullet profile is specifically designed to optimize function and feeding in M16/M4 variant guns. The cartridge’s propellant technology is custom designed to enhance weapon operation, and delivers phenomenal temperature stability. The cases are manufactured to mil-spec hardness and feature staked and sealed primers and sealed case mouths.


Intended for use in and performs optimally in a 1:9" twist barrel.

*All 5.56 NATO ballistics gelatin shots were taken from 30 feet.*

Interesting that no barrel lengths limitations are mentioned for this round.
Could this be a better one for a 10.5 inch barrel?

 

[Broker]

From:
http://www.m4carbine.net/showthread.php?t=19881

For LE Patrol use, where there is a high incidence of potential engagements around or involving vehicles, ammunition that is able to effectively penetrate intermediate barriers, particularly vehicle glass is critical. The best LE 5.56 mm/.223 loads for intermediate barrier penetration using 1/9 and faster twist barrels are the 5.56 mm Federal 62 gr Trophy Bonded Bear Claw (TBBC) bonded JSP (XM556FBIT3) and 5.56 mm Winchester 64 gr solid base bonded JSP (Q3313/RA556B) developed for the FBI, along with the outstanding new Black Hills 5.56 mm 50 gr TSX loading. Note that these are all true 5.56 mm loads that require a real milspec 5.56 mm chamber, not a SAAMI .223 chamber--be sure to check with an appropriate gauge or reamer. Most other acceptable LE barrier blind loadings are at .223 pressures, including the .223 55 & 62 gr Federal bonded JSP Tactical loads (LE223T1 & LE223T3), along with loads using Nosler 60 gr Partition JSP, Remington 62 gr Core-Lokt Ultra Bonded JSP (PRC223R4), .223 Federal 55 gr TSX (T223S), and the .223 Speer 55 & 64 gr Gold Dot JSP's (and identically constructed Federal 62 gr Fusion JSP and Federal XM223SP1 62gr Bonded JSP). The Swift 75 gr Scirocco bonded PT is also good choice, but usually requires a 1/7 twist. Note that the Barnes all copper TSX bullets are great projectiles and offer good penetration through barriers, however, when first hitting a laminated automobile windshield intermediate barrier, most TSX bullets exhibit less expansion than bonded JSP’s, as the Barnes jacket either collapses at the nose, the jacket "petals" fold back against the core, or the "petals" are torn off; this results in a caliber size projectile configured a lot like a full wadcutter, leading to deep penetration. If running 1/12 twist barrels, stick with the BH 50 gr TSX, Fed 55 gr TBBC, Speer 55 gr Gold Dot, or Fed 55 gr TSX. NONE of the fragmenting 5.56 mm OTM bullets, even the heavy 75 - 100 gr loads, offer acceptable performance through automobile windshield glass. Contrary to what many believe, M193 & M855 FMJ are not very good against glass; the best military 5.56 mm load against glass is 52 gr M995 AP, followed by the 62 gr Mk318 Mod0 OTM and 70 gr Optimal "brown tip" OTM.

Short barreled 5.56 mm weapons, such as the Colt Commando, Mk18 CQBR, HK416, HK53, HK G36C, etc… offer advantages in confined spaces. With SBR’s it is best to stick with the barrier blind loads recommended above, although the heavy OTM's suggested for long distance shooting will also work. SBR's can run into rotational velocity issues with some loads, so it is generally best to select faster 1/7 twist barrels whenever possible. Remember, with SBR’s, effective engagement distances are significantly reduced compared to the longer barreled carbines.

Do short barrel 5.56 mm carbines have some limitations? Yes, especially beyond 100 yards, but BFD…learn what they are, train, and drive on. Despite the ballistic compromise, for LE urban work with lots of entries, the 10.5-12.5” BCM, Colt, Centurian, LaRue, LMT Mk18/Commando style weapons w/Aimpoint RDS's are the best weapon types for this mission.

 

[Broker]

The Only Cartridge that Claims 200 yard Effectivness from 10 inch Barrels

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.
Video:

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