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Posted: 12/10/2002 3:08:16 PM EST
[Last Edit: 12/10/2002 4:53:32 PM EST by tatjana]
[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.

Procedure:

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.

Conclusions:

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.
Link Posted: 12/10/2002 3:08:47 PM EST
[Last Edit: 5/6/2004 6:30:34 PM EST by brouhaha]
Other notes and observations:

A. Unlike non-fragmenting experiments with Wolf and GP90, Dr. Brouhaha (Hee!) was heard to exclaim "For crying out loud!" when it became apparent how many fragments he was going to be forced to recover with forceps.

B. Dr. Tatjana (Hee!) exhibited clear signs of glee with the degree of fragmentation. Dr. Tatjana (Tee Hee!) partook of multiple frozen drinks while Dr. Brouhaha (Hee!) performed the extractions.

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



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.
Link Posted: 12/10/2002 3:09:17 PM EST
More to follow...
Link Posted: 12/10/2002 3:10:05 PM EST
[Last Edit: 5/7/2004 9:49:29 AM EST by brouhaha]
Link Posted: 12/10/2002 3:30:32 PM EST
Excellent! So, are these loaded to the "commercial" .223 pressure levels, or the higher 5.56 "military" levels? Can you tell us who manufacturs the bullet, and/or what the Ballistic Coefficient is? thanks -z
Link Posted: 12/10/2002 3:35:55 PM EST
[Last Edit: 5/7/2004 9:49:35 AM EST by brouhaha]

Originally Posted By Zak-Smith:
Excellent!

So, are these loaded to the "commercial" .223 pressure levels, or the higher 5.56 "military" levels?

Can you tell us who manufacturs the bullet, and/or what the Ballistic Coefficient is?

thanks
-z



I can't be too specific no. I can say that the BC is very high. In excess of .400
Link Posted: 12/10/2002 3:40:48 PM EST
what is the OAL of the cartridge?
Link Posted: 12/10/2002 3:51:31 PM EST
[Last Edit: 5/7/2004 9:49:54 AM EST by brouhaha]

Originally Posted By Hoplite:
what is the OAL of the cartridge?





Left: M193, Right: Early Prototype 100 grain Open Tip round.
Link Posted: 12/10/2002 3:52:57 PM EST
[Last Edit: 5/6/2004 6:32:49 PM EST by brouhaha]

Originally Posted By Hoplite:
what is the OAL of the cartridge?




2.255"
Link Posted: 12/10/2002 3:53:54 PM EST
[Last Edit: 12/10/2002 3:56:42 PM EST by sesat_ram]
thanks b&t for all that work. time to order that 22-243 ar10 upper. What is the optimum twist for this round? What is the slowest twist that can stabilize it?
Link Posted: 12/10/2002 3:59:10 PM EST
[Last Edit: 5/7/2004 9:50:03 AM EST by brouhaha]

Originally Posted By sesat_ram:
thanks b&t for all that work.

time to order that 22-243 ar10 upper.

What is the optimum twist for this round? What is the slowest twist that can stabilize it?



I doubt it will stabilize below 1:7 very well. We will be doing long range tests and accuracy tests later.
Link Posted: 12/10/2002 4:21:05 PM EST
A 100 grain bullet in a cartridge that is the same oal as the M193 round has got to have serious velocity issues. Has anyone done any long range chrono work yet? If the M193\M855 round won't fragment well beyond 200 meters, what will this one do?
Link Posted: 12/10/2002 4:32:41 PM EST
[Last Edit: 5/7/2004 9:50:13 AM EST by brouhaha]

Originally Posted By Sgt_Gold:
A 100 grain bullet in a cartridge that is the same oal as the M193 round has got to have serious velocity issues. Has anyone done any long range chrono work yet? If the M193\M855 round won't fragment well beyond 200 meters, what will this one do?



The 100 muzzles at around 2450 but can go higher with some adjustments. It has a very high BC and is still fragmenting down to about 2100 fps. That's a LOT of reach. We'll post more details on reach in our next installment. Stay tuned!
Link Posted: 12/10/2002 4:33:58 PM EST
I take it from the pics and the listed items for testing that this round did not require any additional throating, unlike some of the other commercial offerings which have been noted to be set back in some barrels?
Link Posted: 12/10/2002 4:40:09 PM EST
[Last Edit: 5/6/2004 6:33:09 PM EST by brouhaha]

Originally Posted By ProfGAB101:
I take it from the pics and the listed items for testing that this round did not require any additional throating, unlike some of the other commercial offerings which have been noted to be set back in some barrels?



No, nothing special required for these.

That's what makes them so nice!
Link Posted: 12/10/2002 4:49:47 PM EST
[Last Edit: 5/7/2004 9:50:23 AM EST by brouhaha]

Originally Posted By ProfGAB101:
I take it from the pics and the listed items for testing that this round did not require any additional throating, unlike some of the other commercial offerings which have been noted to be set back in some barrels?



I'm going to edit the experiment text to reflect that the rounds are magazine length more clearly.

But yes, no modifications required. Magazine length. No throating/etc. The only restriction is a tight (1:7) twist. Our test rounds (velocity and gel) were all shot from a single magazine without any reloading.
Link Posted: 12/10/2002 4:54:25 PM EST
Thanks for the prompt clarification. Someone will be set to make a small bundle should this cartridge combo be for sale to the public.
Link Posted: 12/10/2002 5:01:48 PM EST
Tatjana and Brou, Glad to hear that everything worked well! Maybe Tat will get rid of her BM 1:9 and get a really barrel now :) -Kevin
Link Posted: 12/10/2002 5:03:24 PM EST
[Last Edit: 5/7/2004 9:50:31 AM EST by brouhaha]

Originally Posted By CANADIAN_TACTICAL:
Tatjana and Brou,

Glad to hear that everything worked well!

Maybe Tat will get rid of her BM 1:9 and get a really barrel now :)


-Kevin



Depends on the results of the upcoming TAP 75, 77 SMK and 80 grain tests. :)
Link Posted: 12/10/2002 5:28:56 PM EST
Tat, Just bugging you - looking forward to those tests. (a second note I have to learn how to spell/type - really barrel - come on Kevin - real barrel)
Link Posted: 12/10/2002 5:32:08 PM EST
Silly Question? Why are you guys rooting around manually extracting the fragments from the slices? I'm fairly sure that alcohol dissolves gelatin (or is that acetone, anyhow I know SOMETHING dissolves gelatin). why not put the sections in a shallow tray and then cover with a solvent, wait a little while and recover the fragments from the liquid.
Link Posted: 12/10/2002 5:39:40 PM EST
[Last Edit: 5/7/2004 9:50:40 AM EST by brouhaha]

Originally Posted By Katana16j:
Silly Question?

Why are you guys rooting around manually extracting the fragments from the slices?

I'm fairly sure that alcohol dissolves gelatin (or is that acetone, anyhow I know SOMETHING dissolves gelatin).

why not put the sections in a shallow tray and then cover with a solvent, wait a little while and recover the fragments from the liquid.



When you say "liquid" above, you mean the hypersticky and viscous liquid that gets all over everything before starting to mold and smell bad such that your friends and family ask "have you been playing in the graveyard late at night again...?" That liquid? :)

(Can you tell we tried this once?)
Link Posted: 12/10/2002 6:45:53 PM EST
wow, that's some impressive fragmentation. I can't wait to see how it performs at longer ranges. I'm even more excited at the possibility that it'll become commercially available, so little ol' me can buy some. I'm gonna go over to TFL and post about this, and give 'em a link. Maybe we'll get some new membership, too.
Link Posted: 12/10/2002 6:52:43 PM EST
[Last Edit: 12/10/2002 6:55:05 PM EST by new-arguy]
Hahahahaha, Brou and Tatj are stinky! Hahahaha! Awesome testing you two. Is there a snowballs chance in hell we'll see any of this ammo, or something similar available on the commercial market? Oh, and BTW, where are your credentials and lab notes and the bibliography? Are you qualified to be giving this info? I hope you're smirking, that was a joke! [:P]
Link Posted: 12/10/2002 6:54:20 PM EST
[Last Edit: 5/7/2004 9:50:54 AM EST by brouhaha]

Originally Posted By new-arguy:
Hahahahaha, Brou and Tatj are stinky! Hahahaha! Awesome testing you two. Is there a snowballs chance in hell we'll see any of this ammo, or something similar available on the commercial market?



"I see plans within plans...."

;)
Link Posted: 12/10/2002 6:55:34 PM EST
[Last Edit: 5/6/2004 6:33:33 PM EST by brouhaha]

Originally Posted By new-arguy:
Is there a snowballs chance in hell we'll see any of this ammo, or something similar available on the commercial market?



I guess that depends on how cold Hell is.

It's all up to the military and the manufacturer. So we have no clue.
Link Posted: 12/10/2002 8:21:44 PM EST
T&B Awesome work, fully jives with the other work I've seen. Excellent, and thanks for forgoing the scientwist metric nonsense, I didn't have to reach for my metre stick even once. :D One question tho, can you give me measurement on the projo itself? OAL and length from cannelure to base? If you can't answer I guess I can scale the dims off of your comparison pic. BTW, who's this copper red gal anyway? She's friggin hot.
Link Posted: 12/10/2002 8:34:57 PM EST
[Last Edit: 5/6/2004 6:33:41 PM EST by brouhaha]
On the commercial market?



It's all up to the military and the manufacturer. So we have no clue.



How could the military have a say? They don't legislate, though I suppose they could "disfavor" a certain manufacturer...

Once the recipe is figured out, if there is a market, some company will satisfy the demand. Since the bullet materials aren't exotic, there should be no legal barriers to civilian sales.

Does anyone who can say know the manufacturer of the bullets themselves? Or any other 100gr offering? I bet some hand-loaders could figure out a suitable recipe without too much trouble.

-z
Link Posted: 12/10/2002 10:18:56 PM EST
[Last Edit: 5/6/2004 6:33:49 PM EST by brouhaha]

Originally Posted By tatjana:
Depends on the results of the upcoming TAP 75, 77 SMK and 80 grain tests. :)



Hey, what about the 69 SMK loads? Or is there enough evidence of their performance already out there?
Link Posted: 12/10/2002 10:36:57 PM EST
69 grain works with the 1/9 twist and they are doing studies on bullets that work with the 1/7 twist. OK I am going to ask a lot of questions so please bear with me. Can you say if the bullet... Is jacket in a match type jacket (base jacketed also where the open tip is caused by manufacturing process) or is it open at the rear? Is there anything special about the jacket we cant see (internal serrations etc) or is it just a thin jacket? Also... In the pic of the low penetrating round was the jacket material in the last inch of gel from the base of the bullet that penetrated the deepest? Was the piece that penetrated the deepest a jacketed piece of the bullet or just a lead fragment. Do you think that the under penetrating round was caused by jacket seperation from the "piece" that seems to be traveling the 14" when it stays together? (if that is the case) Sorry for so many questions... Will you be performing tests with 14.5" barrels? Will you be reloading with reduced charges to provide the velocity to simulate gelatin results at various ranges or can you tell us the fragmenting range of various barrel lengths based on the muzzle velocity and BC combined with the 2100 fragmenting threshold of this bullet? Where does the 2100 fps fragmentation threshold figure come from? What ranges will your accuracy testing be done at and will you be using both a 20" and 14.5" barrel? (20" 1/9 handles the 75 grain better than the 14.5" because of the higher velocity so I assume the same may be true here) What kind of frozen alcholic beverages were being consumed?
Link Posted: 12/11/2002 3:27:11 AM EST
[Last Edit: 5/7/2004 9:51:32 AM EST by brouhaha]

Originally Posted By DevL:
69 grain works with the 1/9 twist and they are doing studies on bullets that work with the 1/7 twist.



We will probably do some 69 grain for public consumption before we are done.


OK I am going to ask a lot of questions so please bear with me.


No problem.


Can you say if the bullet...

Is jacket in a match type jacket (base jacketed also where the open tip is caused by manufacturing process) or is it open at the rear?



It's a closed base.


Is there anything special about the jacket we cant see (internal serrations etc) or is it just a thin jacket?


Neither really. It's not particularly thin nor does it have any special structure. We think the massive fragmentation is from the very high surface area presented when the bullet yaws, because of it's length.


Also...

In the pic of the low penetrating round was the jacket material in the last inch of gel from the base of the bullet that penetrated the deepest?



If you're asking was the material that did the most penetrating also material that was from the base of the round: Yes, that was towards the bottom- the base of the jacket is visible in our fragment extraction picture. The lowest, as with all, ended up travelling tail first at the end of its path.


Was the piece that penetrated the deepest a jacketed piece of the bullet or just a lead fragment.


With the lowest penetrating round it was both a jacket piece and a lead hunk, seperated.


Remains of the lowest penetrating round recovered from the 10-11th inch of gel


I think I have these identified right- I'm doing them from memory. Brou will have to confirm.


Do you think that the under penetrating round was caused by jacket separation from the "piece" that seems to be traveling the 14" when it stays together? (if that is the case)


This was one of our theories, that it was a fluke and the jacket acted like an airbrake/parachute in front of the lead chunk (or something). We think it an unusual side effect with this particular shot.


Sorry for so many questions...

Will you be performing tests with 14.5" barrels?



Not sure. Depends how our supply holds out.


Will you be reloading with reduced charges to provide the velocity to simulate gelatin results at various ranges


No. We considered this but now believe that with all gel shots it won't represent the actual conditions of ranged shots. We will be testing terminal effects at lower velocity by actually shooting at range.


or can you tell us the fragmenting range of various barrel lengths based on the muzzle velocity and BC combined with the 2100 fragmenting threshold of this bullet?


Probably could, but I think instead we are going to just shoot them at range with a similar barrel length and use actual experimental data to show fragmentation. Performance can be extrapolated for shorter barrels by shooting for velocity only at range.


Where does the 2100 fps fragmentation threshold figure come from?


Sorry, that I can't share. :(


What ranges will your accuracy testing be done at and will you be using both a 20" and 14.5" barrel? (20" 1/9 handles the 75 grain better than the 14.5" because of the higher velocity so I assume the same may be true here)


Probably 100, 150 and (accuracy permitting) 200 meters.


What kind of frozen alcholic beverages were being consumed?


I'm a huge fan of cheap, overly sweet Pina Coladas and Daiquaris. I'm still upset that Brou wouldn't consider testing one of the experimental rounds in his not-so-cheap Sig- but I came up with that suggestion after a pair of Pinas, so maybe it was ill advised.

-Tat "Hold my Pina Colada and watch this..." jana
Link Posted: 12/11/2002 4:31:51 AM EST
[Last Edit: 5/6/2004 6:34:02 PM EST by brouhaha]

Originally Posted By Zak-Smith:
I bet some hand-loaders could figure out a suitable recipe without too much trouble.
-z



A 100 grain bullet seated to magazine length is 10 pounds of s%^* in a 2 pound bag. The round WILL have an extremely compressed powder charge.

My 77 grain bullet loads are just under being compressed. Imagine adding 23 more grains of bullet in there.

It will not be easy to get good velocity without a chronograph, trial and error, knowledge and a little luck.
Link Posted: 12/11/2002 5:10:27 AM EST
[Last Edit: 5/6/2004 6:34:14 PM EST by brouhaha]


A 100 grain bullet seated to magazine length is 10 pounds of s%^* in a 2 pound bag. The round WILL have an extremely compressed powder charge.

My 77 grain bullet loads are just under being compressed. Imagine adding 23 more grains of bullet in there. <http://www.ar15.com/forums/images/smiles/anim_shock.gif>

It will not be easy to get good velocity without a chronograph, trial and error, knowledge and a little luck.


Check, check, and check. :D

If I can get my hands on some 100gr bullets, and a 1:7 twist barrel with a 5.56 NATO chamber, I'm willing to try it. The load is going to need a dense yet slow powder.

Tatjana, can you tell us: what type of powder was used (e.g. flake, stick) and/or what the charge was?

-z
Link Posted: 12/11/2002 6:26:23 AM EST
According to my ballistic program on my computer: If the initial velocity is 2450 fps and the BC is .400 for the 100 gr bullet; the 2100 fps fragmentation threshold is reached at about 160 yards. It remains supersonic until about 750 yards. The trajectory is somewhat like this: Zero: 200 yards (in AR w/ sights high above bore). Mid range max height above line of sight: 2.2 inches @ 125 yds. 300 yards: 10.3 inches below line of sight. This load does not seem to push the effective range of the 5.56 out further than other loads. It just appears to be more effective within the current effective range. Am I missing anything here? Kent
Link Posted: 12/11/2002 6:57:36 AM EST
[Last Edit: 12/11/2002 7:58:17 AM EST by Zak-Smith]
From this thread, we know the MV from a 20" barrel is about 2450 fps. On ammo-oracle, it says that when fired from a 16" barrel, the round is at about 2100 fps at 200m. So if we use the 16"/200m velocity and the 20"/muzzle velocity to back-calculate the BC, we should get a BC value that is lower than the actual BC, since the 16" will start off with less velocity than the 20". Using a ballistic program based on the G1 drag model, I get the following using a MV of 2457 fps. BC 0.450 -> v=2058 at 200m BC 0.470 -> v=2073 at 200m BC 0.480 -> v=2080 at 200m BC 0.500 -> v=2095 at 200m BC 0.510 -> v=2101 at 200m So, does this mean that the BC is at LEAST around 0.500 ??? By the way, my ballistic program also agress that a BC=0.400 at MV=2450 will drop below 2100fps around 160meters. In "Understanding Firearm Ballistics" by Rinker, the a formula for BC is SD/CF where the SD is the mass in lbs div by PI/4*diameter^2, and the CF is form-factor dependent. This means that the CF (Coefficient of Form) of this bullet is going to be AT MOST 0.91, for a BC of 0.400. -z PS. Edited to add: BC 0.400 -> 2011fps at 200m
Link Posted: 12/11/2002 7:00:06 AM EST
[Last Edit: 5/6/2004 6:34:27 PM EST by brouhaha]

Originally Posted By Zak-Smith:
can you tell us: what type of powder was used (e.g. flake, stick) and/or what the charge was?



I can tell you that it is stick powder. The charge will remain confidential due to liability reasons.
Link Posted: 12/11/2002 7:01:48 AM EST
Someone wanted the projectile length. Since tatjana has posted pictures with scale, it's not too hard to estimate its length. My back-of-the-envelope calculation is about 28.3mm, or 1.115", based on the relative size of the dime... -z
Link Posted: 12/11/2002 7:15:34 AM EST
[Last Edit: 5/6/2004 6:34:38 PM EST by brouhaha]

Originally Posted By Green_Canoe:
the 2100 fps fragmentation threshold is reached at about 160 yards.



We never said that was a "threshold". In the Oracle, we said "...maintain their fragmentation down to below 2100 fps..."

Again...this is something we are no able to be specific about.
Link Posted: 12/11/2002 7:35:55 AM EST
[Last Edit: 5/6/2004 6:35:40 PM EST by brouhaha]

Originally Posted By brouhaha:

Originally Posted By Green_Canoe:
the 2100 fps fragmentation threshold is reached at about 160 yards.



We never said that was a "threshold". In the Oracle, we said "...maintain their fragmentation down to below 2100 fps..."

Again...this is something we are no able to be specific about.



OK. I hadn't reread the Oracle. I was basing my concusions solely on the info in this thread. It's hard to calculate without all the pertinent info available.

Based on Zak's posts I wonder if he is onto something with the BC being up in the .5 range provided the info he is working with valid.

BTW thanks for another great test.

Kent
Link Posted: 12/11/2002 7:36:11 AM EST
[Last Edit: 5/6/2004 6:35:53 PM EST by brouhaha]

Originally Posted By Zak-Smith:
Someone wanted the projectile length. Since tatjana has posted pictures with scale, it's not too hard to estimate its length. My back-of-the-envelope calculation is about 28.3mm, or 1.115", based on the relative size of the dime...

-z



Very close! 1.155"
Link Posted: 12/11/2002 7:41:04 AM EST
[Last Edit: 5/6/2004 6:36:08 PM EST by brouhaha]

Originally Posted By tatjana:
I'm a huge fan of cheap, overly sweet Pina Coladas and Daiquaris. I'm still upset that Brou wouldn't consider testing one of the experimental rounds in his not-so-cheap Sig- but I came up with that suggestion after a pair of Pinas, so maybe it was ill advised.



Heck...the mere suggestion made me ill!

We'll discuss the photo that you posted here later. I seem to remember it a little differently, but I don't have the photos with me at work to edit.
Link Posted: 12/11/2002 7:51:41 AM EST
Great information. Thanks not only to Tatjana and Brouhaha; but to those that helped them and the realoaders/armchair ballisticians in this thread helping crunch the numbers.
Link Posted: 12/11/2002 8:01:15 AM EST
[Last Edit: 5/7/2004 9:51:52 AM EST by brouhaha]

Originally Posted By Zak-Smith:


A 100 grain bullet seated to magazine length is 10 pounds of s%^* in a 2 pound bag. The round WILL have an extremely compressed powder charge.

My 77 grain bullet loads are just under being compressed. Imagine adding 23 more grains of bullet in there. <http://www.ar15.com/forums/images/smiles/anim_shock.gif>

It will not be easy to get good velocity without a chronograph, trial and error, knowledge and a little luck.


Check, check, and check. :D

If I can get my hands on some 100gr bullets, and a 1:7 twist barrel with a 5.56 NATO chamber, I'm willing to try it. The load is going to need a dense yet slow powder.

Tatjana, can you tell us: what type of powder was used (e.g. flake, stick) and/or what the charge was?

-z



Sorry, I can't.

Eventually we'll release some details and try to help the reloaders out. Right now I can't.

Wait till we do some more testing at range anyhow. It could be a dog at 100 meters. I doubt it. I'm very excited about this round. We'll see.
Link Posted: 12/11/2002 8:04:16 AM EST
[Last Edit: 5/7/2004 9:52:03 AM EST by brouhaha]

Originally Posted By Green_Canoe:
According to my ballistic program on my computer:

If the initial velocity is 2450 fps and the BC is .400 for the 100 gr bullet; the 2100 fps fragmentation threshold is reached at about 160 yards.



It's substantially higher than .400. We expect that the fragmentation reach will be somewhat farther and even have reason to believe 2100 fps is a high estimate for the fragmentation threshold. (I think it might be more around 1900-1950, but I don't want to commit just yet). That's about all I can say.



It remains supersonic until about 750 yards.

The trajectory is somewhat like this:

Zero: 200 yards (in AR w/ sights high above bore).

Mid range max height above line of sight: 2.2 inches @ 125 yds.

300 yards: 10.3 inches below line of sight.

This load does not seem to push the effective range of the 5.56 out further than other loads. It just appears to be more effective within the current effective range. Am I missing anything here?



Aside from the BC, no. You're about right.

It's a big "rainbow" trajectory. It's not going to be useful/practical out past, oh, 300 meters, if that. We're not worried about that application, however. We're worried about 200 meters and under where it has the potential to be among the most deadly of .223's (if gel is any measure).
Link Posted: 12/11/2002 8:04:49 AM EST
Just great, now I have to some how convince bushmaster to get me a 1:7 barrel. Actually as Tatjana stated, I'll just wait for the testing of the other rounds first. I truly can't wait to see this 100gr. round tested in a 16" barrel.
Link Posted: 12/11/2002 8:37:25 AM EST
[Last Edit: 5/7/2004 9:52:14 AM EST by brouhaha]

Originally Posted By brouhaha:

Originally Posted By tatjana:
I'm a huge fan of cheap, overly sweet Pina Coladas and Daiquaris. I'm still upset that Brou wouldn't consider testing one of the experimental rounds in his not-so-cheap Sig- but I came up with that suggestion after a pair of Pinas, so maybe it was ill advised.



Heck...the mere suggestion made me ill!

We'll discuss the photo that you posted here later. I seem to remember it a little differently, but I don't have the photos with me at work to edit.



Woops. You were right.

Corrections posted.
Link Posted: 12/11/2002 9:41:44 AM EST
Just wanted to thank you guys for all the great information you have put out!
Link Posted: 12/11/2002 11:30:32 AM EST
[Last Edit: 5/6/2004 6:35:29 PM EST by brouhaha]

Originally Posted By velocity:
Just great, now I have to some how convince bushmaster to get me a 1:7 barrel. Actually as Tatjana stated, I'll just wait for the testing of the other rounds first. I truly can't wait to see this 100gr. round tested in a 16" barrel.



Bushmaster does not make a 16" 1/7 barrel (though I know someone who is petitioning them to ) they do however make a 1/7 M4 barrel from time to time. I just aquired a DOE contract overrun barrel just for these new super long/heavy loads.
Link Posted: 12/11/2002 5:47:43 PM EST
Would I be correct in saying that it would be almost imposible to have a matching tracer for this 100gr. round?
Link Posted: 12/11/2002 7:00:39 PM EST
[Last Edit: 5/6/2004 6:36:39 PM EST by brouhaha]

Originally Posted By ragtop71:
Would I be correct in saying that it would be almost imposible to have a matching tracer for this 100gr. round?



You could have a tracer of matching length, but I HIGHLY doubt you could have a tracer of equal weight.

Take a look at the pic of the 5 bullets. Notice how much longer the M856 is than the M855. You would end up adding about the same length to the 100gr bullet. You would end up with even more loss of powder capacity, not to mention the increased length may require a faster twist than the military standard of 1/7".
Link Posted: 12/11/2002 7:19:36 PM EST
I could be wrong but... IMHO (disclaimer cause I could be RTFO) This round is not being looked at as a cross the board replacement for M855. A tracer is not needed in this bullets intended role. This round is more of a speciality closer range (<200m)round to provide people that predominantly work in that environment with a very effective round.
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