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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 |
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I can't be too specific no. I can say that the BC is very high. In excess of .400 |
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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? |
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I doubt it will stabilize below 1:7 very well. We will be doing long range tests and accuracy tests later. |
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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?
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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! |
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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?
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No, nothing special required for these. That's what makes them so nice! |
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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. |
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Thanks for the prompt clarification. Someone will be set to make a small bundle should this cartridge combo be for sale to the public.
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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 |
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Depends on the results of the upcoming TAP 75, 77 SMK and 80 grain tests. :) |
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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) |
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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. |
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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?) |
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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. |
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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] |
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"I see plans within plans...." ;) |
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I guess that depends on how cold Hell is. It's all up to the military and the manufacturer. So we have no clue. |
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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. |
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On the commercial market?
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 |
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Hey, what about the 69 SMK loads? Or is there enough evidence of their performance already out there? |
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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? |
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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. |
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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 |
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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 |
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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 |
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I can tell you that it is stick powder. The charge will remain confidential due to liability reasons. |
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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 |
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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. |
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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 |
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Very close! 1.155" |
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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. |
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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.
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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. |
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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.
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). |
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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.
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Woops. You were right. Corrections posted. |
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Just wanted to thank you guys for all the great information you have put out!
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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. |
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Would I be correct in saying that it would be almost imposible to have a matching tracer for this 100gr. round?
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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". |
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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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