The themes for today's presentation:

Airport Buggie Personnel

B&T Labs Fragmentation Experiment #3:

"High Velocity 5.56mm 63 grain 'GP90' performance in bare gelatin."

Tatjana von E. and Derek W. F.

Note: We have rescheduled the multi-round testing. It will now be Experiment #4 or #5.

This experiment was designed to assess the terminal performance and wounding properties of Swiss GP90 ammo in 10% calibrated ballistic gelatin. Readers may recall that the Swiss are particularly sensitive to humanitarian issues with respect to terminal ballistics and have made efforts in the international community to reduce the use of fragmenting small arms rounds. As such we were particularly interested to review the terminal performance of the main 5.56 Swiss military round, the GP90 (Gewehrpatrone 90).

specifics and conditions:

Ammo: 63 grain Swiss GP90 Copper Alloy Jacketed FMJBT. Lot PS 524. Headstamp: "T 93"

B&T Labs would like to extend very special thanks to Eric the Ammoman <shameless plug>(Where the price you see is the price you pay)</shameless plug>. (Well, except for this time where the price was $0.00 since Ammoman generously donated the rounds for testing purposes).

Rifle: Preban Bushmaster A3 with M4 profile 16" 1:9 barrel and Phantom flashhider.

Temp: 93 degrees F. 65% humidity.

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.

Dr. Brouhaha (Tee Hee!) made exceptional progress with respect to gelatin preparation with an ingenious use of two postban semi-auto stirrers and one pre-ban fully automatic stirrer. Legal counsel was consulted before the use of the pre-ban stirrer. (Gel is stubborn about dissolving in water below 37 degrees C.).

Pre-ban fully automatic, select fire, black, pistol gripped, magazine fed,
gel agitator, two postban semi-auto stirrers.

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 was calibrated with a .177 caliber BB at 591 fps immediately before testing. The BB penetrated 8.5 centimeters. (Optimum = 8.5cm @ 590 fps). These results are within accepted calibration standards for ballistic testing without penetration measurement adjustment.

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

Two separate shots were made.

The blocks were examined, photographed and then dissected to extract any visible fragments and to measure cross sections of the wound profiles.

Both shots exhibited similar ballistic performance.

Results notes/Observations:

1. Velocity before gel impact for the displayed block was 2811 fps. As with Experiment #2 (Wolf) this is quite low for a 16" shot from 15 feet but as the round is heavier (63 grains v. 55 grains) this was to be expected. Testing rounds before gel shots were of equivalent velocities. Note: This ammo was impressively consistent in terms of velocity. 12 rounds (including 10 test shots and 2 gel shots) averaged 2808 fps. High velocity was 2815 fps. Low velocity was 2801 fps.

2. As with Experiment #2 the rounds exhibited minimal fragmentation- though slightly more than 55 grain Wolf, probably due to the increased length of the bullet. Also as with Experiment #2 all fragmentation was apparently a result of the "toothpaste" effect- some lead core was squeezed out of the base of the projectiles as they flattened while traveling sideways in tissue. The deposit of most fragments between 8 and 12 inches bears this means of fragmentation out as the round was traveling sideways in gelatin in these areas. Slightly increased fragmentation compared to 55 grain Wolf appears to have occurred primarily during this sideways travel of GP90. The jackets remained intact throughout. Recovered weight of the projectiles minus fragments were 57 and 59 grains- probably quite near the original weight of the projectiles.

3. The rounds showed flattening from the side and on the base, probably because of "tail first" travel through the gelatin.

4. The rounds began to yaw at ~2.00" and ~2.25" from gel face impact.

5. Both rounds started to veer after 6.5" of penetration. Penetration was 16.25" and 16.50" for tested rounds. One round nearly exited the gel block at 16.25"

6. Both rounds pivoted 180 degrees during their gel travel and ended their path "tail first."

7. GP90 appears to be well sealed. Sealant was visible on pulled and fired bullets and in primer pockets.

GP90 63 grain ammo is resistant to fragmentation at least up to 2811 fps. Swiss GP90 is designed to reduce wounding properties for humanitarian reasons so this was not surprising and is consistent with other results.

GP90 veers as much as 30-45 degrees in tissue after around 6-6.5". 2 of 2 rounds tested exhibited this behavior.

After sectioning it was clear that wound cavity volume throughout is far smaller than with M193 or other fragmenting rounds. Wound cavity volume was similar to Wolf. Interestingly, fractures in the gelatin were more pronounced than with Wolf which otherwise exhibited similar performance. This may be due to the increased weight (despite similar velocity) of the GP90 round v. Wolf.

Because of limited wounding capacity and veering in tissue/gel GP90 is unlikely to provide ideal terminal performance for defensive purposes from 16" weapons and is accordingly not recommended by B&T labs as a defensive round. It is, however, very consistent and accurate- particularly for a military round.

Other notes and observations:

A. As with Experiment #2, Dr. Brouhaha (Hee!) exhibited clear signs of relief (and engaged in some taunting) when the GP90 rounds did not fragment dramatically in Gel. Clearly, Dr. Brouhaha (Hee!) did not enjoy the fragment recovery process in Experiment #1.

B. Dr. Tatjana (Hee!) exhibited clear signs of disappointment (was heard to exclaim "Awww, damn, AGAIN?") when the rounds did not fragment. Dr. Tatjana (Tee Hee!) partook of frozen drinks regardless and amid much whining about knee injuries sustained prior to the experiment.

C. .177 caliber BB calibration (8.5 cm @ 591 fps) was ASTOUNDINGLY close to optimum. (Optimum = 8.5cm @ 590 fps). Dr. Brouhaha's (Tee Hee!) gel cooking skills and Daisy 880 BB gun marksmanship/operator excellence should be noted.

Coming soon: Experiment #4 (Rescheduled, multiple rounds, title to be announced).

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

GP90 ammo on ubercool Sig55x plastic strippers

Headstamp close-up ("T 93" indicates Thun manufacture) for identification

For comparison, left to right, 63 grain GP90, 55 grain Wolf FMJ, 55 grain South African M193,
Millennium Edition collectable United States Roosevelt $0.10 piece (for scale).

For comparison, left to right, unfired 63 grain GP90, 63 grain GP90 after close encounter with 10% calibrated ballistic gel @ 2811 fps,
Millennium Edition collectable United States Roosevelt $0.10 piece (for scale).

Fragment recovery chart by inches from gel face after GP90 close encounter with 10% calibrated gel block @ 2811 fps.
Note: Fragment smiley face pattern in 10-11" section resulted from clandestine operation executed prior to photographic record creation by Dr. Brouhaha and inspired by high rum content of Dr. Tatjana's frozen drink.

10% calibrated ballistic gelatin block after close encounter with 63 grain GP90 @ 2811 fps