B&T Ammo Labs Fragmentation Experiment #7:

"Multiple Round, High Velocity 5.56mm 61.7 grain Tracer (M856) performance in bare gel."

Tatjana von E. and Derek W. F.

This experiment was designed as an excuse to shoot more M856 tracer under the guise of scientific experimentation for terminal performance of the round in 10% calibrated ballistic gelatin.

Note that some discrepancies in weight of tracer rounds exists.  While FM 23-14 lists 63.7 grains as the weight of the bullet IMI, the manufacturer of the L-110 tracer bullet, lists it as 61.7 grains.  We believe the latter figure to be more accurate.

It is probably redundant to say that the outstanding support of the AR15.com community makes this experiment possible. Nevertheless, the outstanding support of the AR15.com community makes this experiment possible.  Special thanks to Eric the Ammoman who's quick delivery and excellent service meant that we have had far too many tracers for far too long.  (Please slow down delivery in future to help alleviate this problem).

Also, as always, thanks to AR15.com member "Hi-Vel" for the gel molds.

If we forgot you please let us know.

Specifics and Conditions:

Ammo: 5.56, 61.7 grain Copper Alloy Jacketed tracer (L-110) rounds with cannelure.  (M856).

Rifle: Pre-ban 16" Colt M4 1:7 upper on a Bushmaster lower.

Temp: 85 F
Humidity: 60%
Altitude: 215 ASL

The target was a FBI spec block (20x20x50cm) of 10% ballistic gel (9 parts water, 1 part gelatin by weight). Vyse ballistic gel was prepared according to FBI ballistic gel testing protocols. Additionally, gel temperature was not permitted to exceed 37 degrees C at any time during preparation.

Following preparation, gel was stored at ~4 degrees C and permitted to cure for 72 hours before testing. Gel was tested within 15 minutes after removal of blocks from refrigeration. Gel blocks were calibrated with a .177 caliber BB immediately before testing. (Optimum = 8.5cm @ 590 fps). Our results (8.55cm) were well within accepted calibration standards for ballistic testing without penetration measurement adjustment.

Procedure:

Velocity tests on the rounds were conducted using a Oehler Research 35P chronograph 15 feet from the muzzle.

After some alignment shots, targets (bare gel blocks) were placed 16 feet from the muzzle and each subjected to a single round. Velocity of the projectile was again measured at 15 feet, 1 foot before the gelatin block.

Multiple blocks were shot.  We are now out of gel and have to buy a bunch more.  This bothers Dr. Tatjana because gel is made from Horsies.

The blocks were examined, photographed and then dissected into slices. Slices were photographed to measure and record wound profile size. Fragments were then extracted and their penetration depth measured and recorded. Fragments were organized according to penetration depth and photographed to record fragment distribution throughout the wound cavity.

The ammunition was quite consistent in gel- but not the way you might think.  Probably as a result of the length of the round, all shots exhibited a significant course deviation mid-gel and just after yaw, before exiting the side of the gel block at around 12-13"

Results notes/Observations:

Velocity of the displayed gel shot was 2954 fps.

Fragmentation of the rounds was nearly absent.

Total penetration (before exit from the block) averaged 12.5" and would probably exceed 13.5" if not for bullet exit.

Neck length (as defined by distance before a significant degree rotation of the round) was generally around 5.75-6".

The largest recovered fragments typically appear to be the bullet's base and rear jacket structures and core.

Recovered materials included 0.2gr of ash and 50.6gr of jacket/core.  Given the lack of fragments it seems clear that upwards of 10gr of bullet weight is tracer element.

Wound cavity size at its extreme was a dramatic 6.3" at inch 7.  This is probably the result of the unusual length of the round.

Recovered Weight:
50.8 gr

Fragmentation:
N/A

Neck:
5.75"

Conclusions:

Surprisingly the M856 does not fragment well at all.  Minimal fragmentation was observed even at 16" muzzle velocity.  Despite this the round does leave a rather impressive wound cavity, though it is not until deep in tissue (6-7") that the cavity opens up significantly.  Accordingly, the round is not recommended for self defense applications.

Other notes and observations:

Total lack of fragmentation was extensive enough to cause Dr. Brouhaha (hee!) to dance for joy before the extraction process. Immediately after the shot he was heard to exclaim: "Ah HA!"  This is generally an indicator of poor levels of terminal performance.

The orange paint used to distinguish the M856 tracer was left smeared inside the first 1-1.5" of the wound cavity.  Dr. Tatjana will consult with S.P.E.C.T.E.R. about developing toxic paint coatings for future deployment.

Tracer elements appear to light IMMEDIATELY (10-20 meters) after exiting the barrel.  Much past discussion about a 50-100 meter delay (including field manual notes) seems to be inaccurate.

We did not observe any scorching of the gel block, though the tracer element exited the block before coming to a rest and burning on some of the backstop material.  Dr. Brouhaha will be reupping his fire insurance immediately.

Damage (temporary/permanent cavity) to the blocks were often so severe in the 5-7" range that sectional slices were hard to hold together.

Note: Neither Dr. Tatjana nor Dr. Brouhaha are Doctors of anything, they have, however, stayed at Holiday Inn Expresses.



Left to Right: M193, M196, M855, M856, Nosler 77gr OTM


M856 High Velocity Encounter with Balistic Gel


Recovered Fragments by Gel Depth


Fragments and Ash Close-up


Recovered Fragments (Detail)


Sectional View of Inch 5-6 of Gel
Dime Shown for Scale.  Blocks 20cm in Width


Sectional View of Inch 6-7 of Gel
Dime Shown for Scale.  Blocks 20cm in Width

Nice to see you back Tat. I had been wondering about the terminal affects of tracer rounds. Hehe Those hogs...

 I never expected gel experiments on tracer rounds, haha.  Nice work tat, and thank you to those involved that made this and all gel tests possible!

Quoted:  I never expected gel experiments on tracer rounds, haha.  Nice work tat, and thank you to those involved that made this and all gel tests possible!

Remember to choose B&T Ammo Labs for all your ballistic testing entertainment needs.  We do birthdays too!  (You must show proof of age).

Ladies, no bachelorette parties, please.

so, uh, do we get to see pictures of this "rather impressive wound cavity" or are we simply left to our imaginations?

edited to amend:  the gel photo is showing up now, so it's all peachy-keen!

This does bring up a good point though, one I had thought about previously.  The 77 grain is much longer, and thus even if it does not fragment will create a much larger wound cavity and much larger temporary cavity than the 55 grain when it tumbles.  It's lethality when not fragmenting could even be approching that of the Russian 5.45mm round, if not equaling/exceeding it.

Remember to choose B&T Ammo Labs for all your ballistic testing entertainment needs. We do birthdays too! (You must show proof of age).

Hey, I have a birthday coming up in January (and you know my age...I think), so what are my chances of getting some gel testing of various 9mm, .40 cal and .45 ACP Winchester Ranger and Speer Gold Dot ammo as my gift? Heck, I'll even supply the ammo! Besides, these don't tend to produce much in the way of fragments, so poor Brou wouldn't be spending as much time digging around in the gel goo collecting them. I might also throw in some 68 gr Black Hills .223 if interested. It seems this is popular with the 1:9 twist people around here. Ahhhhh, gel testing, the gift that keeps on giving!

BTW, great job on the M856 test. As always, you two do some excellent work. I had never even considered testing tracers until now. It sounds like an excellent idea though and the results prove exactly why. Thanks for sharing.

-Charging Handle

Very cool!  Thanks for sharing your work!

DNS

Quoted: so, uh, do we get to see pictures of this "rather impressive wound cavity" or are we simply left to our imaginations? edited to amend:  the gel photo is showing up now, so it's all peachy-keen!

Now updated with sectionals at the extreme cavity depths.  Also added this text:

Damage (temporary/permanent cavity) to the blocks were often so severe in the 5-7" range that sectional slices were hard to hold together.

i got to thinkin' about this, and wondered something.

the tracers burn as they are fired, right.  wouldn't that make some mild wound cotterization that might make the round slightly less effective.  in short, shooting a living target with a tracer might seal the wound it had just created.  this would obviously cause immense pain, but not incapacitation, as the target's not gonna "bleed out" as quickly.

is there any merit to this thinking?

So in basic terms, the round is a horseshit performer?

This is why I stick with my Q3131A

Edits to fix code after board move.

BTW, Troy.  I just noticed your question.  They were indeed steel jacketed.