5.56: Fragmentation or Expansion?

[BallisticHarmony]

My question is which wounding mechanism is more effective if you remove The Hague Convention from the equation? Fragmenting bullets have a more restrictive velocity requirement in which they are effective, but from what I understand they are more lethal than expanding bullets in most situations. Which one is optimal? Is the best solution one that combines both mechanisms, such as the 77 TMK?

Which round has the lowest fragmention threshold?

Which round has the lowest expansion threshold?

Which of the above rounds is more lethal?

Would the M855A1 with a tungsten core (ADVAP) just be the best of all worlds?

[Clint]

Monolithic and bonded expanding styles offer the most consistent terminal performance over the widest range of impact velocities.

[BallisticHarmony]

Monolithic and bonded expanding styles offer the most consistent terminal performance over the widest range of impact velocities.

Would you mind listing a few that you would recommend?

[Defaultmp3]

Would you mind listing a few that you would recommend?

There used to be list on this site...

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.

[BallisticHarmony]

That was an interesting read. I’m still confused as to which option is better if barrier penetration isn’t a factor. Are heavier OTM designs more lethal by default than smaller bonded bullets?

[MegademiC]

Monolithic and bonded expanding styles offer the most consistent terminal performance over the widest range of impact velocities.

...and through the widest variety of barriers.

Edit: fragmenting rounds are slightly more “effective”, but good softpoints are more reliable. You never know when you have a barrier and the gain with soft points is well worth the tradeoff of fragmenting, unless you need the accuracy of OTMs.

Based on my research (DocGKR) and experience (non-combat) id take fusion or similar.
There are Combat SMEs here with experience OCONUS who prefer mk262.

Pick one stock up and train.

[Todd.K]

The FBI is under no bullet design restrictions, and chose a barrier blind expanding load.

Barrier blind gives you more than the haters care to admit. For example, bullets that do well vs the windshield test do well going through bone. Intermediate barriers could end up being the arm of your attacker.

Expanding bullets are more consistent in performance. Fragmenting designs can sometimes fail to fragment, or fragment too much without enough penetration. I'm more open to fragmenting designs in a larger caliber, the 5.56 just starts without much room to loose any bullet weight and go deep enough.

[Doc Safari]

I realize there are probably other threads on this, but since brand names have been mentioned, I'd like to know where Federal Fusion fits in the food chain. (Like my alliteration?)

[d2wing]

Expanding bullets are clearly much better than fragmenting bullets for everything except for small critters. Fragmenting by itself is not reliable.

[yoni]

I had very good results from the IMI 55 grin bullet, I stayed with slow twist barrels and was in a position to hunt them down. I went through multiple barrels through the years but that 55 grain bullet out of my Israeli made commando was great.

Are modern bullets better, sure but if you have a 1 in10 or 1in 12 barrel and 55 grain FMJ bullets don't lose sleep over it.