In honor of my 1000th posting (Hurrah- I'm officially an AR15.com geek!) we are pleased to present, for your perusal, our latest Gelatin test.  Enjoy!

The themes for today's presentation:

1.  NEVER fly America West- even if the flight schedule is better.

2.  Wearing a leg brace, hobbling and looking pathetic lets you ride on the cool airport buggy in Houston, but NOT at O'Hare- even with extended whining and pouting.  Buggie drivers seem to be somewhat less advanced on the evolutionary scale than other airport employees, including security personnel.



Airport Buggie Personnel


Once again from our not-quite-as-new state of the art clandestine lab in a super-secret location, our second official and calibrated testing results:

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.

Procedure:

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.

Conclusions:

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.

Photos (wound profile cross-sections of gel are pending):


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

Looks like a decent practice round. Any plans to test it out of a 20 inch barrel to see if it picks up much velocity?

Quoted: Looks like a decent practice round. Any plans to test it out of a 20 inch barrel to see if it picks up much velocity?

Probably not any time soon.  GP90 isn't designed to fragment really so I don't expect much difference.  We are concentrating on 16" shots for now also.  Once we get the major rounds covered out of 16" shots we might try some of the more "interesting" shots out with 20" weapons.

Simply marvelous. I do so enjoy these tests! Thanks Brou and Tatj!

Awesome!  Learn something everyday!

Excellent work! My hat's off to both of you.  

This is probably insignificant, but I noticed this round yawed and curved upwards, same as M193, but the Wolf ammo you tested curved downwards. Any idea why? I understand why it takes a curved path, but I wonder why one goes up and the other goes down. Not that it's important in the overall scheme of things, it's just a minor detail I noticed.

BTW, that airport buggy monkey looks vaguely familiar to me.

Interesting and hard to get info

- thank you for posting it

I bet it still hurts when it hits you!

Ok, I'll bite.

Whats the story behind the knee?

Quoted: Excellent work! My hat's off to both of you.  www.stopstart.fsnet.co.uk/smilie/thumbs.gif This is probably insignificant, but I noticed this round yawed and curved upwards, same as M193, but the Wolf ammo you tested curved downwards. Any idea why? I understand why it takes a curved path, but I wonder why one goes up and the other goes down. Not that it's important in the overall scheme of things, it's just a minor detail I noticed.

Bullets that flatten seem to have this behavior.  It's probably 99% dependent on the direction of the initial yaw, which is VERY hard to predict.  The bullet, travelling sideways, probably acts like a paddle, or a space shuttle shape, causing it to lift pretty severely.

Obviously, fragmenting bullets don't get a chance to do that, but you do see some curving in the larger fragments since they are irregularly shaped.

BTW, that airport buggy monkey looks vaguely familiar to me.

One of the airport buggie drivers was SUCH a yahoo I just had to include that.  I can't even remember where I found the picture.

Scientific.  Sober.  Enlightening.  Informative.  Funny.  You guys rule.

Hmmm ... did I say "sober"?

Just curious.  What flavor gelatin do you use?  It looks like lemon in the photos, but I can't tell for sure.

Again, this is great info.  Have you given any consideration to recording the barometric pressure and altitude of your experiments?

excellent work, Doctors!!!

and extra points for the presentation

Where does one buy pure gelatine?

In honor of my two thousandth post, I bring you my sincerest thanks for all of your hard work. couldnt think of a better way to spend it!

Humor and knowledge! Great information from both of you and many thanks for sharing what you learned.

Quoted: Where does one buy pure gelatine?

We buy ours straight from Vyse Gelatin.

Ummm.. Just wondering, Tatjana, where have you been all my life?

So. This round OBVIOUSLY has less tendency to fragment than M193/M855. Thanx for the heads up. Does it contain an SS109-type penetrator insert in the nose area?


Scott

Quoted: So. This round OBVIOUSLY has less tendency to fragment than M193/M855. Thanx for the heads up. Does it contain an SS109-type penetrator insert in the nose area?

No penetrator.  The jacket is thicker than normal, but other than that, it's a standard lead bullet.

Derek - any eta for tests #4 and # 5?????

We're working on the logistics of #4 and #5 right now.  I won't give a date, but hopefully it won't be too far off.

looking forward to them :)

SOMETHING TO ADD.....THIS AMMUNITION IS VERY, VERY ACCURATE, SHOOTS CLEAN,(WARM BUT CLEAN) SEALED, AND CHEAP...AS SOON AS I AM ABLE I AM ORDERING PLENTY FROM ERIC(AMMOMAN)..I HAVE SHOT A FEW THOUSAND ROUNDS OF THIS AMMUNITION MOSTLY WITH A 16 IN BULLBARREL FROM J&T DIST IN 1X8 TWIST (AND A FEW LEGAL FULL-AUTOS) NEVER THE SLIGHTEST BURP.THE ACCURACY IS SUPERB AND SHOOTING UNDER 1/2 INCH AT 200 YARDS IS NOT BAD FOR MILITARY SURPLUS TYPE AMMO AND DID I MENTION IT IS CHEAP...I KNOW THAT THERE IS CHEAPER AMMO BUT I WILL NEVER SHOOT LACQUER COATED AMMO IN ANY GUN I OWN..ESPECIALLY A MATCH AR... GOOD TEST GUYS...AMMOMAN IF YOU ARE LISTENING..GET SOME OF THE RAUG 69 GRAIN SWISS
.223 PRETTY PLEASE!!!!

Bump!  Does anyone else even have the addresses saved?  My 75-77 grain file is corrupted or something and I can't bring up up.