[Brouhaha]: "From the land of sky blue waters..."
[Tatjana]: "...Waaah-ters..."
[Brouhaha]: "...From the land of pines, lofty balsam, Comes the beer refreshing, Hamm's the Beer Refreshing."
[Together]: "Haaaaaamm's...."

Well, ok, we can't exactly promise you free beer (even Hamm's), but we can bring you:

B&T Ammo Labs Fragmentation Experiment #4:

"Multiple Round, High Velocity 5.56mm 100 grain performance in bare gel."

Tatjana von E. and Derek W. F.

This experiment was designed to assess the terminal performance and wounding properties of magazine length 100 grain "Open Tip" rounds in 10% calibrated ballistic gelatin. Readers may recall that other ballistic testers have reported the magazine length 100 grain round as among the most impressive terminal performer ever tested. Because of their compatibility with stock AR15s (given a fast twist rate) and the defensive potential these rounds presented we felt testing them to be exceptionally important for our purposes. After some significant efforts we obtained a series of 100 grain rounds for testing. Because of the sensitive nature of the 100 grain rounds and their development, some details of the rounds themselves are withheld.

As usual, the outstanding support of the AR15.com community makes this experiment possible. Particular thanks go to AR15.com member "Hi-Vel" for selflessly fabricating our molds in a hurry (and flat out refusing to be paid) after a disaster with old ones. Thanks to "Captain K." about whom we can say no more. Thanks also to the anonymous AR15.com member who's loading expertise was instrumental in assessing the rounds.

specifics and conditions:

Ammo: .223 100 grain Copper Alloy Jacketed Open Tip rounds.

Rifle: Preban Colt 20" A1 with Government Profile 1:7 Barrel and A2 Flashhider.

Temp: 55 degrees. 60% Humidity. Pressure: 30.19 in/Hg. Alt: 213 feet.

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 were within accepted calibration standards for ballistic testing without penetration measurement adjustment.

10 velocity tests on the rounds were conducted using a Oehler Research 35P chronograph 15 feet from the muzzle. Results are included below:

2476 fps
2456 fps
2503 fps
2447 fps
2454 fps
2457 fps
2430 fps
2460 fps
2476 fps
2411 fps

Calculations on velocity data:

Mean: 2457.0
Median: 2456.5
Standard Deviation: 25.4
Q1: 2442.8
Q3: 2476.0

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.

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.

Shots exhibited similar ballistic performance- only a 3.5" variation in penetration between all shots was observed with one remarkable outlier- which penetrated substantially lower than the group.

The extremes of performance (measured in penetration) are photographically reproduced here, i.e. the Highest ("High") and Lowest ("Low") penetrations in terms of inches of penetration from the gel face are shown.

Results notes/Observations:

1. Velocity of our highest penetrating round ("High") immediately prior to impact with the gel face was 2450 fps.

2. Velocity of our lowest penetrating round ("Low") immediately prior to impact with the gel face was 2440 fps.

3. Velocities mirrored velocities observed in the gel testing of 100 grain rounds in other ballistic experiments of which the authors are aware.

4. Fragmentation of the 100 grain rounds was as dramatic, even more dramatic, than expected. "Spectacular" was a frequently used descriptor. Neck length was very small (generally under .50"), and fragmentation began immediately. The combination of exceptional fragmentation and extremely deep penetration (up to 14.50") makes the round a good defensive option. It should be noted, however, that the "Low" round did not exceed 12" of penetration (10.75" only). Despite this, fragmentation of the "Low" round was explosive. (See Figure C).

5. Initial weight of the projectiles averaged 97.2 grains. Recovered weight of the projectiles averaged 82.2 grains.

6. The largest recovered fragments appeared to be part of the bullet's base and jacket structures. Average largest recovered fragment was 22.5 grains. (76.9% fragmentation). This was usually found at the extreme of the wound cavity. (Inch 12.5-14.5).

7. All rounds appeared to produce two specific cavity "blooms" where larger cavities and more dramatic fragmentation in the gel seem to indicate the bullet was traveling with a 90 angle perpendicular to the direction of travel (See Figures H and I). The "blooms" are joined by a short section of narrower tissue damage. This suggests that the round rotates 180 degrees during the course of travel and as it passes through a 90 degree orientation to the direction of travel twice leaves the dramatic tissue damage and fragmentation seen in the "blooms." Fragmentation and tissue damage in the second "bloom" is the most dramatic. Probably because by the second half of its 180 degree rotation and after having portions of the jacket stripped away the round's [star trek moment]structural integrity[/star trek moment] is minimal and fragmentation more dramatic. Wound cavity at its extreme, measured by gel fractures, was usually in about the 8th inch of penetration and spanned a rather significant 5.75-6". Fragments were often deposited at the extreme edges of these fractures.

8. Some rounds started to veer off their original path after about 10" of penetration. The veer was not generally significant (1" - 1.5" from straight line path).

9. Dramatic fragmentation makes exact determination impossible but all rounds seems to have ended their path "tail first."

10. Fragmentation was so significant and left so many small fragments, primarily of lead core, that there was little hope of recovering them all. Many fragments were far smaller than fine beach sand or table salt crystals.

At close range these rounds are devastating. They are clearly the most dramatic fragmenting and cause the most tissue damage of any .223/5.56 round tested so far. Some concern accompanies the shallow penetration of the "Low" round, but it may very well be compensated for by the exceedingly violent tissue damage exhibited in the gel shots. We also suspect this particular round to be a fluke. Still, additional testing should concentrate on penetration depth.

After sectioning it was clear that wound cavity volume throughout the wound path is FAR greater than with M193 or any other tested fragmenting rounds.

Because of limited penetration of the "Low round" and the uncertainty of fragmentation at lower velocities (e.g. from a 16" weapon), we cannot yet make a defensive recommendation for this round. Pending a resolution of the penetration issue and lower velocity testing we may revise this view.

Figure A: Left to right: M193, M196, M855, M856, 100 grain

Figure B: "High" penetrating 100 grain in gel

Figure C: "Low" penetrating 100 grain in gel

Figure D: Profile closeup of "High" penetrating entry

Figure E: Profile closeup of "Low" penetrating entry

Figure F: Head on closeup of "High" penetrating entry

Figure G: Head on closeup of "Low" penetrating entry

Figure H: "Blooming" highlight view of "High" penetrating round

Figure I: "Blooming" highlight view of "Low" penetrating round

Figure J: Recovered fragments by depth for "Low" penetrating round

Figure K: Recovered fragments by depth for "Low" penetrating round (highlight)

Sectional view of wound cavity from 0 - 11" for "Low" penetrating round. Dime shown for scale. Note: Block width is 20cm.