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Posted: 8/13/2003 7:52:17 AM EST
[Last Edit: 8/13/2003 7:55:10 AM EST by tatjana]
B&T Ammo Labs Fragmentation Experiment #6:

"Multiple Round, High Velocity (NATO Pressure) 5.56mm 77 grain OTM (Mk262 Mod 1) 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, NATO pressure, 77 grain, cannelured, "Open Tip Match" rounds (Mk262 Mod 1) in 10% calibrated ballistic gelatin. These 77 grain rounds are samples provided by Black Hills through distributor Georgia Precision and represent trial loadings for the proposed special order group purchase of the ammo from Black Hills and Georgia Precision.

While SAAMI pressure loadings of various 77 grain rounds are available, the more recent use of heavier rounds with shorter barreled carbines in response to inconsistent and less than ideal performance of lighter (sub 65 grain) rounds at range and from carbines prompted us to seek to specify and test a higher pressure, heavy round in order to increase the range of effective terminal performance from 14.5 and 16" carbines. In addition, we prefer a cannelured round for feeding purposes and reliability. Our goal was to provide a demonstrably viable solution for increased terminal performance from short barreled (14.5-18") carbine systems between 0 and 150-300 meters or beyond.

We believe the Mk262 Mod 1 meets and exceeds our expectations in this respect.

As usual, the outstanding support of the AR15.com community makes this experiment possible. In particular we would like to thank "Tommy" from Georgia Precision, for providing us with samples of the round and Black Hills for lending their manufacturing facilities to our collective project.

Also, we would like to thank AR15.com moderator, Troy for his assistance in generating enough interest in the round to make commercial quantities of interest to Black Hills, "Captain K," who, as usual, we cannot say much about, and AR15.com and Maryland AR15 Site official Forest. Who could forget AR15.com member "Hi-Vel" for the molds that continue to serve us well. Of course, as usual we are probably forgetting many people who were instrumental in the many stages of this project. Hopefully they will forgive our omission.

Specifics and Conditions:

Ammo: .223 77 grain Copper Alloy Jacketed Open Top Match rounds with cannelure. Nosler bullets loaded to NATO (military) pressure specifications in Winchester brass by Black Hills as per special order.

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

Temp: 92 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 (8.4cm) were well 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:

2738
2725
2735
2730
2757<­BR>2712
2719
2741
2729
2744
Mean: 2733 fps.

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.

The ammunition was consistent in gel with all shots exhibiting similar ballistic performance- only a .5" variation in penetration between all shots was observed.

Results notes/Observations:

Velocity of the displayed gel shot was 2734 fps.

Fragmentation of the rounds was dramatic and among the 3 best rounds tested by the authors.

Total penetration averaged 12.5"

Despite the excellent fragmentation, substantial bullet mass typically was retained in one or two larger lead/copper fragments, which typically established the farthest penetration frontiers in the gel. The authors believe this behavior represents a positive sign for this round's tissue performance after barrier interaction.

Neck length was generally around 1.6".

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

Average largest recovered fragment was 34.2 grains (55.6% fragmentation) and was typically found at the extreme of the wound cavity.

Wound cavity size at its extreme was typically 3.875" at inch 4-5 and numerous fragments were deposited at the extreme edges of these fractures, indicating high tissue disruption potential even at the frontiers of the round's tissue disruption.

Comparison to SAAMI pressure 77 grain nosler (no cannelure):

Recovered Weight:
SAAMI 77gr: 74.2gr.
NATO 77 gr: 73.7 gr.

Fragmentation:
SAAMI 77 gr: 58.3%
NATO 77 gr: 55.6%

Largest Recovered Fragment:
SAAMI 77gr: 32.1gr.
NATO 77 gr: 34.2 gr.

Neck:
SAAMI 77gr: 1.57"
NATO 77gr: 1.60"

Conclusions:

The NATO pressure 77 grain OTM is a solid and consistent performer with substantially better fragmentation at close range than M193, M855 and most sub 68 grain rounds. The NATO pressure round will provide fragmentation at ranges between 25-75 meters father than the SAAMI pressure round. The addition of a canellure does not appear to dramatically alter fragmentation, which is as good or better than that of the SAAMI pressure round and equals all heavy (65+ grains) rounds tested excepting the magazine length .223 100 grain OTM round tested by the authors.

Overall gel penetration at the muzzle is lower in the NATO pressure 77 grain round, probably as a result of increased muzzle velocity and the consequent increase in stress the round experiences when passing through tissue simulant. Accordingly, fragmentation is initially more violent and penetration reduced. The authors expect that penetration of the 77 NATO round from a 16" barrel will increase by 2-3" to match the SAAMI penetration (13-14") after travelling between 50 and 70 meters and as velocities reduce. Penetration should then level off near 12.5" until the fragmentation threshold is reached.

Fragmentation of the NATO 77 grain round is more extensive than that of the SAAMI at depths from 7-12 inches. Wound profile at this depth is more extensive as a result.

In summary, the NATO 77 grain OTM round fills an important gap and we believe will substantially increase the terminal performance of 14.5" and 16" civilian weapons systems for practical self defense.
Link Posted: 8/13/2003 7:52:49 AM EST
[Last Edit: 5/6/2004 6:25:23 PM EST by brouhaha]
Other notes and observations:

Fragmentation was extensive enough to cause Dr. Brouhaha (hee!) to utter occasional profanities during the extraction process. This is generally a good indicator of high levels of terminal performance.

Ballistic trajectory of the 77 grain round generally yields a 2" rise at 100 meters and a 8.9" drop at 300 meters using an Improved Battlesight Zero (IBZ) and a 16" barrel. This makes the deployment of these rounds very viable for close to medium (0-300 meter) defensive purposes in combat conditions without any necessity for combat sighting adjustment. (A critical criteria for practical rifle use in self-defense).

Preliminary experiments show that reliable fragmentation for the rounds will extend to at least 225 meters in 16" weapons. The authors have additional reason to believe (but insufficient data as of yet to make a supported claim) that reliable fragmentation may, in fact, extend out to 250 meters from a 16" barrel and 220 meters from a 14.5" barrel. Testing in this area continues.

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

Special Note from Dr. Tatjana: It is so very good to be back.


Figure A: Left to right: M193, M196, M855, M856, 77 grain OTM



Figure B: 77 grain OTM rounds in packaging.



Figure C: 77 grain performance in gel (wide view).



Figure D: 77 grain performance in gel (close up of deep fragmentation).



Figure E: Recovered fragments by depth.



Figure F: Recovered fragments by depth (8-13" closeup).



Figure G: Ballistic performance of the 77 grain round
(left to right, 77 NATO 14.5", 77 NATO 16", 77 SAAMI 16")
(Fragmentation thresholds in red).





Figure H: Ballistic performance of the 77 grain NATO round (16" velocity and drop, 14.5" velocity and drop)
Link Posted: 8/13/2003 7:55:37 AM EST
AWESOME! THANK YOU! SO GLAD YOU DID THIS@!#~#@!$ [:D]
Link Posted: 8/13/2003 8:00:20 AM EST
The 14.5" NATO launches it at 2750fps while the 16" NATO launches it at 2660fps? huh?
Link Posted: 8/13/2003 8:08:14 AM EST
[Last Edit: 5/6/2004 6:26:08 PM EST by brouhaha]

Originally Posted By wyv3rn:
The 14.5" NATO launches it at 2750fps while the 16" NATO launches it at 2660fps? huh?



My fault.

Corrected.
Link Posted: 8/13/2003 8:18:23 AM EST
[Last Edit: 5/6/2004 6:26:40 PM EST by brouhaha]
Thank you so much Tatjana and Brouhaha for yet another wonderful contribution to the AR15.com boards! A toast to you both! *APPLAUDS*
Link Posted: 8/13/2003 9:12:35 AM EST
[Last Edit: 5/6/2004 7:08:21 PM EST by brouhaha]
Excellent post, thanks for doing these expriments!

I'm sure glad I got my 16" 1/7!!! It looks like a great combo with this ammo!
Link Posted: 8/13/2003 9:18:11 AM EST
[Last Edit: 5/6/2004 7:08:13 PM EST by brouhaha]
Thank you very much!

Now we have another test data of 77gr. Looks very good!


Also, this thread doubles as a perfect excuse for buying that 16" upper.
Link Posted: 8/13/2003 9:20:27 AM EST
Tatjana, Great Test - Thanks! BTW its good to have you back. It was may pleasure to help in any way I could. -Forest
Link Posted: 8/13/2003 9:21:17 AM EST
Very cool!
Link Posted: 8/13/2003 9:25:37 AM EST
[Last Edit: 5/6/2004 7:08:00 PM EST by brouhaha]
SHE'S BACK!!



Welcome back, and thanks (yet again) for the good work!
Link Posted: 8/13/2003 9:39:31 AM EST
[Last Edit: 8/13/2003 9:41:39 AM EST by ArmdLbrl]
Yay! You were missed. Damn, those figures on the 77gr are much better than I expected. Wonder how much further the 18.5" SPR barrel or even the plain 20" M16A4 (USMC DMR rifle) would shove the fragmentation threshold out? Maybe 400m for the 20"?
Link Posted: 8/13/2003 10:32:21 AM EST
[Last Edit: 5/6/2004 7:08:31 PM EST by brouhaha]
Link Posted: 8/13/2003 12:35:29 PM EST
[Last Edit: 5/6/2004 6:41:55 PM EST by brouhaha]

Originally Posted By ArmdLbrl:
Wonder how much further the 18.5" SPR barrel or even the plain 20" M16A4 (USMC DMR rifle) would shove the fragmentation threshold out? Maybe 400m for the 20"?



Not much - if you look at the velocity numbers for the 18" & 20" you don't gain a significant amount for the extra barrel length.
Link Posted: 8/13/2003 2:32:43 PM EST
Welcome back Tatjana!
Link Posted: 8/13/2003 2:36:47 PM EST
Welcome back TAT!!!! MM419
Link Posted: 8/13/2003 2:54:06 PM EST
[Last Edit: 5/6/2004 6:27:24 PM EST by brouhaha]

Originally Posted By Forest:

Originally Posted By ArmdLbrl:
Wonder how much further the 18.5" SPR barrel or even the plain 20" M16A4 (USMC DMR rifle) would shove the fragmentation threshold out? Maybe 400m for the 20"?



Not much - if you look at the velocity numbers for the 18" & 20" you don't gain a significant amount for the extra barrel length.



Therefore you have a justified excuse of getting 16" upper for yourself
Link Posted: 8/13/2003 7:02:55 PM EST
[Last Edit: 5/6/2004 6:42:06 PM EST by brouhaha]
"Also, we would like to thank AR15.com moderator, Troy for his assistance in generating enough interest in the round to make commercial quantities of interest to Black Hills"

How commericially available are we talking about?

CRC
Link Posted: 8/13/2003 7:30:16 PM EST
[Last Edit: 8/14/2003 2:42:07 AM EST by GSSP]
Great stuff Tat! Now, if only the BH Red box of 77 gr SMK I just ordered today from Tommy will stabilize from my 16" 1:9 so I can confidently buy some NATO spec stuff from Tommy later. Big Al
Link Posted: 8/14/2003 2:21:17 AM EST
[Last Edit: 5/6/2004 6:27:39 PM EST by brouhaha]

Originally Posted By GSSP:
Great stuff Tat!

Now, what's the suggested minimum velocity for reliable fragmentation which leads us to dertermine max effective range? 2100 fps?



If you want to be really safe, use 2250. That still gets you 200-225 yards from a 16" and 175 from a 14.5". We suspect that 2100 is closer, however.


Now, if only the BH Red box of 77 gr SMK I just ordered today from Tommy will stabilize from my 16" 1:9 so I can confidently buy some NATO spec stuff from Tommy later.

Big Al



We'll try to post some accuracy results from 1:9 barrels.
Link Posted: 8/14/2003 2:23:45 AM EST
[Last Edit: 5/6/2004 6:27:54 PM EST by brouhaha]

Originally Posted By CRC:
"Also, we would like to thank AR15.com moderator, Troy for his assistance in generating enough interest in the round to make commercial quantities of interest to Black Hills"

How commericially available are we talking about?

CRC



www.georgiaprecision.com/cart/items/BHANatoAmmo.htm
Link Posted: 8/14/2003 4:38:45 AM EST
[Last Edit: 8/14/2003 4:40:17 AM EST by Derek45]
Nice work. Anybody know where I can find 77gr. Nosler bullets [b]with cannelure?[/b] I want to load some up with My DILLON 550B I know I saw them for sale, but I forget where.
Link Posted: 8/14/2003 4:55:36 AM EST
OUTSTANDING as usual WB Tat.
Link Posted: 8/14/2003 5:00:16 AM EST
[Last Edit: 5/6/2004 6:25:56 PM EST by brouhaha]

Originally Posted By Derek45:
Nice work.

Anybody know where I can find 77gr. Nosler bullets with cannelure?

I want to load some up with My DILLON 550B

I know I saw them for sale, but I forget where.



There were some cannelured 77gr SMKs for sale a while ago, maybe that's what you recalled?
www.jobrelatedstuff.com/forums/topic.html?b=1&f=10&t=186138
Link Posted: 8/14/2003 9:00:11 AM EST
[Last Edit: 5/6/2004 6:28:02 PM EST by brouhaha]

Originally Posted By Forest:

Originally Posted By ArmdLbrl:
Wonder how much further the 18.5" SPR barrel or even the plain 20" M16A4 (USMC DMR rifle) would shove the fragmentation threshold out? Maybe 400m for the 20"?



Not much - if you look at the velocity numbers for the 18" & 20" you don't gain a significant amount for the extra barrel length.



Why did they build the SPR with its 18.5" barrel then? It must do something?
Link Posted: 8/15/2003 7:58:46 PM EST
Link Posted: 8/16/2003 5:45:58 AM EST
[Last Edit: 5/6/2004 6:28:11 PM EST by brouhaha]

Originally Posted By Troy:
Because the SPR isn't intended to be a standard-issue gun, but more of a "Designated Rifleman's" gun, with LONG(er) range precision in mind.

-Troy



Barrel length has many ramifications for things other than just velocity, or as an extension of velocity. Serious consideration of terminal performance via velocity is only a RECENT development when it comes to weapon design. In the past more important factors have been:

Accuracy.
Ballistics.
Weight.

and my favorite:

Accessorizing!
Link Posted: 8/16/2003 9:52:58 AM EST
[Last Edit: 8/16/2003 10:18:04 AM EST by Charging_Handle]
Welcome back Tatja! It's good to see you around here again. We've all really missed your ammo posts, as they have been very interesting and helpful. It's also nice to see you and the other doctor (do I insert tee-hee here?) doing gel tests again! I have so much trouble spotting these tacked threads that I thought this was the old, initial test....number 5 I believe it was. I only clicked on this by accident and I am sure glad I did. What an excellent round this has turned out to be. If only BH would make this a permanent part of their line-up, I think they would have a gold mine and so would all of us. Thanks again for taking the time to do this and share it with everyone! Also a big thanks to Troy, Forest, Kevin, Tommy and everyone else who helped put this all together and make it a reality. -Charging Handle
Link Posted: 8/18/2003 8:44:20 AM EST
[Last Edit: 5/6/2004 7:08:54 PM EST by brouhaha]
Excellent work. hanks
Link Posted: 8/19/2003 10:27:01 AM EST
Anyone done barrier penetration tests on these loads...as in against auto body steel, wood etc? They look DAMN good against soft living targets, but are they a good general purpose round?
Link Posted: 8/19/2003 1:58:25 PM EST
[Last Edit: 5/6/2004 6:28:26 PM EST by brouhaha]

Originally Posted By Lumpy196:
Anyone done barrier penetration tests on these loads...as in against auto body steel, wood etc?

They look DAMN good against soft living targets, but are they a good general purpose round?



Chews up hard steel plate pretty well.
Just as good as 55FMJ.

My 77gr Nosler / VARGET handloads:




===============================================
I'd love to see somebody do some geletin testing on the 70grain SPEER softpoint. SPEER says it's designed for uh, "larger varmits"
Link Posted: 8/19/2003 2:14:17 PM EST
[Last Edit: 5/6/2004 7:09:02 PM EST by brouhaha]
Nummmyyyyyyyy
Link Posted: 8/20/2003 5:41:13 AM EST
[Last Edit: 5/6/2004 6:42:26 PM EST by brouhaha]

Originally Posted By Lumpy196:
Anyone done barrier penetration tests on these loads...as in against auto body steel, wood etc?

They look DAMN good against soft living targets, but are they a good general purpose round?



Lumpy,

While these are super anti-personnel rounds, they aren't perfect for engaging targets inside vehicles. In fact, the only .223 ammo that I would label good against such barriers are the Federal 55 and 62 gr Trophy Bonded SP loads. Because they are bonded, they retain enough weight and hold together well enough to still be somehat effective on targets inside. The heavy match bullets aren't really bad. But I would have to put them in the same class as M193, M855 and most other .223 rounds, in that they are not ideal for this purpose. While M193, M855 and most other .223 loads will leave holes in various barriers, penetrating those targets often shatters the bullet and many times only fragments will actually reach the intended target. A fragment is unlikely to stop a determined threat. If we could create a big block of gel sometime, place it in the front seat of a car and blast away at it from the outside, I think it would be obvious the shortcomings of most .223 ammo in this regard.

As a civilian, I don't feel my most likely threats will be folks inside vehicles. Therefore I feel the 77 gr Black Hills NATO load would be an excellent choice for me. I feel it would also be a good choice for police entry teams. The arena where I would consider something with better performance qualities against vehicles would be police patrolman duties....where encountering numerous vehicles and people in and around them on a daily basis is routine. In that case I see the following options as being acceptable:

1. Load your AR carbine with the Federal Tactical Trophy Bonded loads. While these will not create a wound as damaging as the 77 gr Nosler bullet, they are adequate and have better performace against glass and autobodies.

2. Load your AR carbine with the 77 gr Black Hills NATO loads, but have your shotgun filled with Brenneke slugs for use against vehicles. These are far better for that purpose that traditional 00 buckshot and 1 oz. Foster slugs.

3. Have you AR set-up as a specialty weapon to use strictly for anti-personnel use outside of vehicles, while having another carbine chambered in .308 loaded with 165 gr Federal Trophy Bonded to deal with barrier threats. The 155 gr AMAX also does well against glass and has far more wounding ability than the best .223 load.

4. Scrap the .223 altogther and use an M1A Scout or an FAL carbine with the 155 gr Hornady AMAX. Since I am a fan of the .223 I saved this as the last option, but included it so the .30 cal folks could not nail me. LOL. If I was placed in a situation where I could only have 1 long gun and I felt there was a high risk of having to engage threats behind barriers, I probably would choose a .308 carbine over the .223 carbines.

Again, it really all comes down to what you are most likely to encounter. If you must use a .223 to defeat barriers, the TBBC would be my choice. Otherwise I would want the 77 gr Black Hills NATO for everything else. Only you can decide what is most appropriate for your particular situation. I hope this was helpful.

-Charging Handle
Link Posted: 8/20/2003 6:41:59 AM EST
[Last Edit: 8/20/2003 6:45:03 AM EST by Lumpy196]
If only those were all available options....
Link Posted: 8/23/2003 10:09:32 PM EST
I have two 16" FALS for use after dark. The plan is to blind them with the muzzle flash and run.
Link Posted: 8/25/2003 7:18:03 PM EST
How did this get demoted? Or do thumbtacks have a time limit?
Link Posted: 8/25/2003 7:59:09 PM EST
[Last Edit: 5/6/2004 6:28:42 PM EST by brouhaha]

Originally Posted By Derek45:

Anybody know where I can find 77gr. Nosler bullets with cannelure?



You could try:

Shooters Pro Shop
(The Official Nosler Store)
107 SW Columbia St.
Bend, OR 97702
541-312-2506

I got a bunch there about a year ago, but I have not had time to load them.

Wombat
Link Posted: 8/26/2003 5:09:02 AM EST
Link Posted: 8/26/2003 5:23:51 AM EST
[Last Edit: 5/6/2004 6:28:51 PM EST by brouhaha]

Originally Posted By Georgia-Precision:
Mods,
How about a tack? This post has some very useful info available.
GPSS



It already is. The post is floating around, but it's included in the "Best of B&T ammolabs" post tacked to the top....
Link Posted: 9/13/2003 12:11:12 PM EST
[Last Edit: 5/6/2004 7:09:14 PM EST by brouhaha]
Question(s): Would the Nosler Custom Competition 77 Grain Hollow Point Boat Tail, without cannelure also work as well? Also, what would I be looking at for a powder charge weight - say WW 748 powder (that's what I use the most) - or a different powder? Any (well... almost any ) suggestions are welcome. Thanks,
Mike.
Link Posted: 9/13/2003 12:42:48 PM EST
Mike, As I understand it, the bullet you mention is the same as in the NATO load sans the cannulure. Thier is load data on the Nosler web site as well as the potential to use the Sierra data for their 77 gr SMK. Why do I know this. I'm getting ready to load my own 77 Nosler's or SMK's for "practice" ammo that will shoot to the similiar POA as the NATO stuff I have on order. Big Al
Link Posted: 9/13/2003 1:02:09 PM EST
[Last Edit: 5/6/2004 6:29:02 PM EST by brouhaha]

Originally Posted By patrad:
Question(s): Would the Nosler Custom Competition 77 Grain Hollow Point Boat Tail, without cannelure also work as well? Also, what would I be looking at for a powder charge weight - say WW 748 powder (that's what I use the most) - or a different powder? Any (well... almost any ) suggestions are welcome. Thanks,
Mike.



Try some VARGET


Link Posted: 9/13/2003 4:22:24 PM EST
GSSP & Derek45 - Thanks a bunch guys. I appreciate the info. I suspected as much regarding the bullet. I'll see what I can cook up. Carry on! Mike.
Link Posted: 9/17/2003 11:12:18 AM EST
Based on the info on this and other sites, my brother-in-law and I just bought a case. Hope it works out well in my M4gery and his AR-15 full size. They both have 1/7 twists so things should be all right.
Link Posted: 10/17/2003 5:46:10 AM EST
Does anyone with a 20" barrel have velocity figures for these rounds?
Link Posted: 10/17/2003 6:06:29 AM EST
Imposter, I don't have much time right now, but if you can wait a few weeks (maybe 3) I should be able to post some velocities from a 18" and 20".
Link Posted: 10/17/2003 6:17:53 AM EST
[Last Edit: 5/6/2004 6:29:11 PM EST by brouhaha]

Originally Posted By imposter:
Does anyone with a 20" barrel have velocity figures for these rounds?



From my tests:

20" Chrome Lined Bushmaster (1:9 twist)
77gr Nosler (Mk262 Mod 1) 2790fps @ 10'
78degF, 37% hum, 1200' ASL

Shoot can't find my ones from my 75gr testing, I'll have to repeat the tests.

From an 18" SPR barrel:
77gr Nosler (Mk 262 Mod1) 2821fps @ 10'
77gr SMK (Black Hills) 2776fps @ 10'
75gr Hornady OTM (Black Hills) 2745fps @ 10'
86degF, 46% hum, 300' ASL
Link Posted: 10/29/2003 4:14:44 AM EST
Thanks all, for some great info! I'm sure my 1/7 20" will like!
Link Posted: 11/8/2003 2:23:24 PM EST
This looks like the ultimate AR-15 load, for any 1/7 twist barrel. The GPSS website says that the velocities of the 77 OTM out of a 20" barrel is supposed to be 2900+ fps....HOT damn !!!
Link Posted: 11/25/2003 4:32:24 PM EST
Any updates on velocities out of 20" 1/7 twist barrels ??? TIA :)
Link Posted: 5/3/2004 9:23:28 AM EST
[Last Edit: 5/3/2004 9:27:10 AM EST by 123whisper]
Just figured I would toss this back up to the top Are we going to get the rest of the B&T ammolab tests retacked?
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