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Thread: 5.56 mm Duty Loads

  1. #1
    S.M.E. & STAFF DocGKR's Avatar
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    5.56 mm Duty Loads

    3/1/17

    Only after proper foundational and ongoing repetitive refresher training, cultivating warrior mind-set, and ensuring weapon system reliability do you need to worry about ammunition selection. Most folks would be far better off practicing with what they have, rather than worrying about what is "best". As long as you know your what your weapon and ammo can realistically accomplish, it is all just a matter of training and shot placement. I would much rather go into battle with a guy who practices 15,000 rounds a year using generic 55 gr FMJ out of his old M16A1 than with some guy that has the latest state-of-the-art ammo and rifle, but only shoots 500 rounds a year. If you need to delve into the arcane subject of agency duty ammunition selection, below are the state of the art choices in 5.56 mm/.223:

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    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. The Hornady 5.56 mm 55 gr GMX is another acceptable option. 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), .223 Horn 55 gr GMX, and the .223 Speer 62/64 gr Gold Dot JSP's (and identically constructed Federal 62 gr Fusion JSP and Federal XM223SP1 62gr Bonded JSP). The Speer 75 gr Gold Dot JSP and Swift 75 gr Scirocco bonded PT are also good choices, but usually require 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, Fed 55 gr TSX, Horn 55 gr GMX, or Speer 55 gr Gold Dot. 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.

    In those situations where intermediate barrier penetration is not a critical requirement, for example LE urban entries or long range shots in open conditions, then OTM, JHP, and standard JSP loads can offer acceptable performance. For 1/7 twist barrels, the Hornady 75 gr OTM, Nosler 77 gr OTM, and Sierra 77 gr SMK OTM are all good choices. The experimental BH loaded 100 gr OTM exhibits impressive fragmentation, even at relatively low velocities, however while capable of shooting out to 600, it is optimized for 200 and under. If stuck with 1/9 twist barrels, the heavy 70+ gr loads are not universally accurate in all rifles and the 69 gr SMK OTM, the 68 gr Hornady OTM, the Winchester 64 gr JSP (RA223R2), the Federal 64 gr TRU (T223L) JSP, Hornady 60 gr JSP, are likely to run accurately in the majority of 1/9 twist rifles. Again it is critical to keep in mind that the above loads fail to offer adequate penetration through intermediate barriers.

    For longer range engagements using precision weapons like the Mk12 SPR or DMR rifles with faster 1/8 or 1/7 twist barrels, one of the combat proven 5.56 mm (ie. 5.56 mm NATO pressure loads, not .223 SAAMI pressure loads which run about 200 f/s slower) heavy OTM loadings are a good choice: the Barnes 70 gr TSX (Optimized "browntip"), Hornady 75 gr TAP (#8126N), Nosler 77 gr, or the Sierra 77 gr Match King (Mk262 Mod1) and 77 gr Tipped Match King.

    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.

    Keep in mind, that with non-fragmenting bullet designs, heavier bullet weights are not necessarily better, especially at closer ranges and from shorter barrels. As long as penetration and upset remain adequate, it is possible to use lighter weight non-fragmenting bullets and still have outstanding terminal performance. With fragmenting designs, a heavier bullet is ideal, as it provides more potential fragments and still allows the central core to have enough mass for adequate penetration. In addition, heavier bullets may have an advantage at longer ranges due to better BC and less wind drift.

    Whatever projectile is used, it is best with a cannelure to prevent bullet set-back in semi-auto/auto weapons. Also, be cautious with the exposed lead on some JSP designs. Often they will run great for up to 200-300 rounds, but then mysterious feeding failures will begin as a result of lead build-up on the feed ramps. I have personally seen this occur with a variety of JSP's including 55 gr, 60 gr, and 64 gr in LE training courses. As soon as FMJ or OTM was substituted, all the feeding failures ceased.

    Be sure to watch your ammo storage conditions. Temperatures above 150 deg F will degrade the powder and cause pressure spikes. Hint: Think locked metal conex containers in the mid-east, car trunks in the southern U.S., and storage areas near heaters in the northern U.S. Also be cautions of leaving a round in a very hot chamber; besides the obvious danger of a cook-off, the powder can also be damaged by the heat, leading to dramatically increased pressures when the round is eventually fired.

    A large SWAT team in this area had a failure to fire from an M4 with Hornady TAP ammo during an entry--fortunately no officers were hurt and the suspect immediately threw down his weapon when the carbine went click instead of bang. After the incident was concluded, the team went to the range and expended the rest of their carbine ammo and had one additional failure to fire. This same team had 3 Hornady TAP rounds fail to fire in training a couple of years ago. When Pat Rogers was teaching a class at a nearby agency, there were 5 failures to fire using Hornady TAP ammo. In all 10 cases, there appeared to be good primer strikes, but no rounds fired. On analysis, the ammunition had powder and checked out otherwise.



    However, despite what appeared to be good primer strikes, two problems were discovered. First, when accurately measured, some of the primer strikes had insufficient firing pin indentations. The failed round from the potential OIS incident had a primer strike of only .013"—the minimum firing pin indent for ignition is .017". In addition, the primers on the other rounds were discovered to have been damaged from repeated chambering. When the same cartridge is repeatedly chambered in the AR15, the floating firing pin lightly taps the primer; with repeated taps, the primer compound gets crushed, resulting in inadequate ignition characteristics--despite what appears to be a normal firing pin impression. Once a round has been chambered, DO NOT RE-CHAMBER IT for duty use. Do NOT re-chamber it again, except for training. This is CRITICAL!!!

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    Many LE agencies around here used the Hornady 75 gr TAP OTM, Winchester 64 gr JSP (it was on the state contract for very low cost), and similar Fed 64 gr JSP TRU load (223L)--all have worked well in actual officer involved shootings against unobstructed targets. However in the wake of the serious terminal performance failures by non-bonded .223 64 gr JSP's due to inadequate penetration into the criminal's Toyota Tundra truck in the July 2010 CHP OIS incident in Oakland, quite a few agencies here switched to general issue of Barrier Blind loads like the 55 & 64 gr Gold Dot loads, along with the 55 & 62 gr TBBC loads that previously saw more limited use.

    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. For GP LE Patrol use, properly built AR15's like the 14.5-16” BCM, Colt, LMT, LaRue, Centurian carbines with Aimpoint RDS's and 3x magnifiers in quick detach flip mounts like the LaRue LT649 are superb choices (quality variable optics like a S&B 1.1-4x Short Dot, NF 1.1-4x, or Trijicon 1-4x are also good options) -- pick the right tool for the job.
    Last edited by DocGKR; 03-07-2017 at 11:45 AM.
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  2. #2
    S.M.E. & STAFF DocGKR's Avatar
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    The Black Hills produced Mk262 uses the 77 gr Sierra Match King (SMK) OTM and is built as premium quality ammunition intended for precise long-range semi-auto rifle shots from the Mk12 rifle. It is great for its intended purpose. Mk262 has demonstrated improved accuracy, greater effective range, and more consistent performance at all distances compared to M855 when fired from current M16, Mk12, M4, HK416, and Mk18 rifles and carbines. However, despite this substantially improved performance, Mk262 is NOT necessarily the best choice for LE or most military combat use from carbines, as Mk262 still manifests the problems of poor intermediate barrier penetration and somewhat variable terminal performance inherent with the SMK design, as well as increased cost.

    As articulated by combat AAR’s the last few years and demonstrated in recent military wound ballistic testing, improved combat ammunition that is specifically designed for rifle and carbine use, not machine guns, is urgently needed. New loads should offer:

    -- JAG approval
    -- Full reliability in diverse environmental extremes
    -- A thermally stable propellant
    -- Consistent lot-to-lot and shot-to-shot performance, even when fired from short barrel weapons
    -- Crimped and sealed primer
    -- Sealed case mouth
    -- Cannelure for functional reliability in adverse conditions
    -- Decreased muzzle flash
    -- Acceptable accuracy at 300-500m
    -- Good soft tissue terminal performance (early consistent bullet upset within 1 or 2 inches of initial tissue penetration
    -- 12 to 18 inches of penetration coupled with maximized tissue damage during the first 10 to 12 inches of travel in tissue
    -- Designed to minimize AOA and fleet yaw issues
    -- Blind to Barriers

    OTM, although a step forward, does not fully provide what is needed in a military setting. Until recently this goal seemed impossible, however “Barrier Blind” ammunition requirements from multiple organizations, including the FBI, USMC, NSWC Crane/USSOCOM, & JSOC have yielded several options from industry that appear to effectively address this issue. For example, see the 01 June 2006 Marine Corps RFI (http://www.cbd-net.com/index.php/search/show/1087257) for “Barrier Blind” ammunition. NSWC Crane (http://www.dtic.mil/ndia/2009i...aysessioniii8524.pdf) has now publicly acknowledged the existence of the SOST cartridges, the 5.56 mm 62 gr Mk318 Mod0 OTM; this is a non-bonded version of the ATK TOTM projectile made for the Marine Corps Barrier Blind RFI, as noted on page 12 of my NDIA briefing from 2008 (http://www.dtic.mil/ndia/2008Intl/Roberts.pdf). The SOST rounds are optimized for relatively short barrel weapons, use heat stable, flash suppressed powder, and offer good terminal performance, with early upset and reasonably good intermediate barrier performance for a non-bonded projectile. The SOST/TOTM is an outstanding, simple, adaptive design--projectiles can be manufactured with a traditional lead core or in a lead-free version, bonded or non-bonded. The 70 gr Optimal "brown tip" in use by some SOF organizations is another excellent option.

    At this time, given the current ammo choices available via the standard green/white side military supply system, for a general purpose carbine, I'd load my mags with Mk318 Mod0 if available. For long range shooting the Mk262 Mod1 is optimal. A couple of mags of M995 AP for barriers wouldn't be a bad idea either.

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