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Posted: 11/25/2008 4:59:34 AM EST
I had time to chrono SSA's new Barnes TSX loads to confirm velocity figures as posted on their website.  This bullet is an all copper (monolith) design, which exhibits extreme penetration and controlled expansion with high % weight retention.

These loads, upon which I report, are factory loadings now available from SSA.
             
PLEASE NOTE:  SSA now reports that the line of 85 TSX's are not going to be designated as "combat" or "commercial."  This, IMO, is a great thing.  I have long disliked the need for a delineation, because companies like DPMS still make chambers that are dangerously tight, and cause both confusion, and a watering down of the 6.8 SPC load.  However, according to Art at SSA, the 85 grain TSX is light enough, and has gas rings which reduce bearing surface area, enough that this load doesn't generate as much of an over-pressure in improperly spec'd guns, like the 1 in 10" SAAMI (or super-tight, tighter than SAAMI DPMS), 6 groove guns.  Personally, I wish those "older" models would just go away once and for all, so that we can get on with things.


I shot both the Cardinal Armory 16" superlight barrel, and my 12.5" Cardinal Armory barrel, as well, to compare velocity figures.  The latter barrel has been fire lapped with Tubbs Final Finish, and I can recommend that treatment as accuracy definitely improved following the treatment, but most notably after about 10 "fouling" rounds had been fired.  I suppose that is because the barrel is cleaned so much during and immediately after the treatment.  Expect at least 5 "fouling shots" after doing the Tubbs Final Finish
.

Both barrels are Chrome lined, SPCII chambered, 4 groove 1 X 11" twist rifling...proper specs, IMO.

I apologize that I don't have pictures of groups, because I focused upon velocity here.  When you shoot through a chrono, you are more interested in NOT hitting the upright supports .  I did it once, and Constructor did it once, so I now line everything up and keep it there when using the chrono.

Here are the velocities.  The 6.8 will NEVER be the same, gentlemen


-16" Cardinal Armory superlight 16" shooting SSA's Barnes TSX, 85 grain bullet

-3101 FPS
-3093 FPS
-3114 FPS
-3103 FPS

AVG. Vel. 3102 FPS


-12.5"  Cardinal Armory lapped barrel, shooting SSA's Barnes TSX, 85 grain bullet

-2974 FPS
-2972 FPS
-2987 FPS
-2970 FPS

Avg Vel. 2975 FPS  



These numbers are as expected.  The 16" barrel gives about 127 FPS more than the 12.5.  This equates to 36.3 FPS per inch, as we have seen so many other times.  Ergo, long gone are the notions that 6.8 SPC cannot generate proportional additional velocity with an increase in barrel length.  This occurs with most powders, up to 26 inches, but there is little practicality in using anything of this length.

The most salient point which should be taken from this is that the 6.8 SPC is so efficient, that it can burn enough of its powder charge in very short barrels, to generate some striking velocities.  Thus, you can go to the 11.5, 12.5 or 14.5 inch barrel without giving up a huge amount of terminal performance, as has been the criticism of the 5.56mm (such as M855) when fired out of the 14.5" M4 versus the 20" M16.  

––Please call or email Barnes and ask for them to make the .277 TIPPED TSX (TTSX) in these weights, i.e 85, 90, or 100 grain.  There is a 110, but it is 1.196" long and a challenge to reload.

––I just received my ARPerformance 20", 12 twist, 3 groove, so I will report vel. and accuracy figures for this barrel once I get it into the field.

––Accuracy figures and velocity test of the GS Custom, 80 grain monolithic bullet (my handloads) are forthcoming.....Enjoy.



missing
Link Posted: 11/25/2008 7:03:33 AM EST
[#1]
Thanks hi-tech-rancher. I keep looking at the velocity for a 12.5 inch barrel. That's solid performance out of a SBR. And just think, that's an off the shelf commercial ammo. No one can say that's a hopped up over-pressured handload.

More people need to contact DPMS and have them correct their chambers. Everyone with a DPMS 6.8 needs to get their chamber checked and reamed out to DMR or SPC II specs. Their newer rifles and carbines are 1:11 twist which would make a very good performance value if they changed their chamber specs.
Link Posted: 11/25/2008 7:41:50 AM EST
[#2]
Wow, that's pretty friggin' cool.   So, given that it's a solid copper bullet, is the BC high enough that it carries well out past 600-800 meters or are we still better off using heavier bullets for long range?
Link Posted: 11/25/2008 7:49:20 AM EST
[#3]
I need a barrel, who has them? This thing looks to good to keep sitting on.

Thanks for the work/info
Link Posted: 11/25/2008 8:57:33 AM EST
[#4]
Quoted:

The most salient point which should be taken from this is that the 6.8 SPC is so efficient, that it can burn enough of its powder charge in very short barrels, to generate some striking velocities.  Thus, you can go to the 11.5, 12.5 or 14.5 inch barrel without giving up a huge amount of terminal performance, as has been the criticism of the 5.56mm (such as M855) when fired out of the 14.5" M4 versus the 20" M16.  




Every cartridge burns its powder in the first few inches of barrel. It has nothing to do with efficiency.
Link Posted: 11/25/2008 8:58:21 AM EST
[#5]
Thanks for posting the tests HTR. I've been curious about the SSA 85 ever since they came out. Now we have real world tests.

FYI. I emailed Barnes ealier today requesting a tipped 90-95gr TSX.
Link Posted: 11/25/2008 9:15:58 AM EST
[#6]
Quoted:
Quoted:

The most salient point which should be taken from this is that the 6.8 SPC is so efficient, that it can burn enough of its powder charge in very short barrels, to generate some striking velocities.  Thus, you can go to the 11.5, 12.5 or 14.5 inch barrel without giving up a huge amount of terminal performance, as has been the criticism of the 5.56mm (such as M855) when fired out of the 14.5" M4 versus the 20" M16.  




Every cartridge burns its powder in the first few inches of barrel. It has nothing to do with efficiency.


Not true, otherwise you wouldn't get fireballs from mosins, bmg or my friend's carbon15.
Link Posted: 11/25/2008 9:19:04 AM EST
[#7]
Link Posted: 11/25/2008 9:26:15 AM EST
[#8]
based on  a .246 ballistic coefficient which may be generous for an 85grn .277 bullet @ 3100 fps, barnes is well known for padding thier BC numbers, the energy figures at range calculate as follows

muzzle 1814 ft lbs of energy

100yds/ 1404 ft lbs of energy/ +1.59"

200yds/ 1072 ft lbs of energy/ ZERO

300yds/ 805 ft lbs of energy/ -7.80"

400yds/ 594 ft lbs of energy/ -23.76"

500yds/ 433 ft lbs of energy/ -51.08"

600yds/ 317 ft lbs of energy/ -94.27"




So, given that it's a solid copper bullet, is the BC high enough that it carries well out past 600-800 meters or are we still better off using heavier bullets for long range?


with any rifle cartridge under the sun faster but with a lower BC almost never out paces a slower heavier higher BC load. When the 5.56 guys want to reach out past 300m they don't reach for a box of 45grn bullets they grab some 69grn+ projectiles


Not true, otherwise you wouldn't get fireballs from mosins, bmg or my friend's carbon15.


the fireball has more to do with the large volume of superheated gas escaping the muzzle into the oxygen rich environment of our atmosphere. But I assure you all of the powder that was going to ignite did so in the first 3 or 4 inches of bullet travel.
Link Posted: 11/25/2008 9:38:05 AM EST
[#9]
The BC of the 85gr TSX is .246   ....

http://www.barnesbullets.com/products/rifle/tsx-bullet/

Goes transonic between 650yds - 750yds.

Which by the way, is pretty damn good from a 16" carbine.
Link Posted: 11/25/2008 9:47:46 AM EST
[#10]
Quoted:
The BC of the 85gr TSX is .246   ....

http://www.barnesbullets.com/products/rifle/tsx-bullet/

Goes transonic between 650yds - 750yds.

Which by the way, is pretty damn good from a 16" carbine.


numbers adjusted
Link Posted: 11/25/2008 3:55:51 PM EST
[#11]
Quoted:
I need a barrel, who has them? This thing looks to good to keep sitting on.

Thanks for the work/info



Want a hot off the press 6.8 barrel? Check out the new Noveske 1:12 twist 6.8 barrels also with an improved SPC II type chamber.

Denny's and White Oak Armament have some good 1:11 SPC II 6-groove also.

AR15Performance.com has some new 6.8 barrels coming around the first of the year. One a match grade chrome lined model, the other rumored to be a LW50 poly.

Stag has a new Model 7 Hunter with a 20 inch 1:11 SPC 4-groove stainless.
Link Posted: 11/25/2008 4:00:58 PM EST
[#12]
Quoted:Want a hot off the press 6.8 barrel? Check out the new Noveske 1:12 twist 6.8 barrels also with an improved SPC II type chamber.


Are the barrels available separately yet?
Link Posted: 11/25/2008 4:40:43 PM EST
[#13]
Quoted:
Quoted:Want a hot off the press 6.8 barrel? Check out the new Noveske 1:12 twist 6.8 barrels also with an improved SPC II type chamber.


Are the barrels available separately yet?


There are very few barrels available separately at this time.  Denny's has the WOA barrels for sale separately, but given the huge spike in popularity and the Obama-cluster$*%~, they are few and far between.

Try Denny, Harrison at ARPerformance and keep watching the EE.  Every so oftehn someone sells one.  If it is 1 X 11 or 1X 12 with SPCII or DMR chamber, jump on it right then.  I recommend that you do not waste your time on a 1X10, SAAMI barrel.

Stags new model 7L (I think that is the name) looks really promising, as they very adroitly went with the 1 X 11 twist, 4 groove rifling and SPCII chamber.  The 20.77" barrel length is a little queer, but you can probably lop that 0.77" off and thread with precision 5/8 X 24 and use a suppressor.

My hat is off to Stag  
Link Posted: 11/25/2008 4:56:59 PM EST
[#14]
I got a question for all the 6.8 guys.  Let me preface first im not picking sides of the 6x battlefield.  I plan on getting a 6.8 upper from harrison as soon as Jan. rolls around, and I have a 6.5G.


Why do the 68 guys keep trying to get the bullets to higher and higher velocities, and the 6.5 guys dont?

Personally I would like to see the 6.5 go a litle faster.  Anyways thought I would ask
Link Posted: 11/25/2008 4:57:18 PM EST
[#15]
Quoted:
The BC of the 85gr TSX is .246   ....

http://www.barnesbullets.com/products/rifle/tsx-bullet/

Goes transonic between 650yds - 750yds.

Which by the way, is pretty damn good from a 16" carbine.


Couldn't agree more.  What other cartridge, can throw an 85 grain projo at 3102 FPS from a rifle which weighs 5.75 lbs, and has a 25 round magazine capacity, and a 16 inch barrel?
What other cartridge can throw a 110 grain Barnes TTSX at 2700 FPS, form a 16 superlight carbine?  Are there any other cartridges which can produce 2975 FPS using an all-copper 85 grain bullet, an AR-15 lower and a 12.5 inch barrel?  No. (but there is an aluminum bullet for the .458 SOCOM...87 grains? that is kinda' neat.)

Efficiency is about the parent case.  Only the 6mm BR is more efficient in terms of the case capacity and its ability to produce velocity.  It has less to do with how much powder burns in the barrel than it does cartridges which are short, and fit in the mag well, yet can still produce velocity like this from short barrels.  That was the kind of efficiency to which I was referring, but I probably didn't state it very adeptly.

I mentioned the Barnes TTSX, because that bullet has even better terminal performance and BC than the TSX.  Give me a 100 grainer that is about 1.05" long and I'll show you some very badly torn up s*%&
Link Posted: 11/25/2008 5:06:07 PM EST
[#16]
Quoted:
I got a question for all the 6.8 guys.  Let me preface first im not picking sides of the 6x battlefield.  I plan on getting a 6.8 upper from harrison as soon as Jan. rolls around, and I have a 6.5G.


Why do the 68 guys keep trying to get the bullets to higher and higher velocities, and the 6.5 guys dont?

Personally I would like to see the 6.5 go a litle faster.  Anyways thought I would ask


Great question:

Here's my answer.  Please also understand that while I love the 6.8 SPC, I also like the Grendel very much, too and feel both are an improvement over the 5.56.

The Grendel has a pressure maximum, set by Bill Alexander which prevents the velocity figures from being increased much over what you see now.  If you exceed the current Grendel velocities, you start to see parts and bolt breakage.  That is not a criticism, rather a simple fact of the design and its ceilings.

The 6.8 SPC still had a LOT of room to grow when it was released.  the SAAMI drawings were not optimized, and of course, the "tinkeres" shooters, engineers and reloaders knew this.  So, we set out to evolve the cartridge, POST-release.

We knew that the velocity that Remington originally claimed (115 grain projectile going 2800 FPS from a 24" barrel) was possible, but they couldn't ever achieve that without severe pressure problems because the powder they used got too hot in the heat of the desert and thus the problems started right then.  Primers leaked and were blowing, but they had set the stage once they released these numbers, and we set out to re-duplicate them

The formula??  It was the powders, chamber, the rifling design and the twist rate.  Once we started testing barrels that had the right specs, we then saw the velocities coming into their own.

Now, you are seeing the velocities of which this cartridge is truly capable.
Link Posted: 11/25/2008 5:47:57 PM EST
[#17]
This bullet should preform very well out to about 200 yrds.  However, the BC (0.246) is not overly impressive and the SD (sectional density= 0.158) is pretty low as well. Given the low SD I suspect that the penetration potential drops off after about 300 yrds. Here is a discussion on the relation between sectional density and penetration. (http://www.chuckhawks.com/sd.htm)

Here is a link to a "Guns and Hunting" article be Aaron Carter on the performance of Barnes 30 cal. 130 gr bullets at different impact velocities.  Basically the design of Barnes bullets is such that they start behaving like solids once the velocity drops below ~2000 fps. Here is a photo from the article showing the Barnes bullet performance.


From "Aaron Carter, Guns and Hunting"

6.8mm 85g ballistics
6.8mm 85g ballistics
Range__Velocity__Energy(Ft-lbs)
100____2719_______1396
200____2358_______1049
300____2025________774
400____1722________559
500____1456________400
600____1239________290
700____1085________222
800_____987________184
JBM [http://www.eskimo.com/~jbm]

320pf

Fixed the links
Link Posted: 11/25/2008 6:18:52 PM EST
[#18]
Link Posted: 11/25/2008 7:41:20 PM EST
[#19]
Quoted:


Comming from an engineering background I agree the velocity figures are impressive.

But to what end are we doing this?

What does a 3000 fps 85gr .277 all copper projectile do that a 2700 fps 110gr .277 all copper projectile can't?

I've been playing with the 110gr bullets because their BCs are all well over .300 which helps at longer ranges.  What is the hyper velocity 85gr get us (other than cool points?).

I figure I'm missing something, or it fills gap that I have not perceived as needed filling?

Thanks.

Kind of my point.  At what velocities do you go " OK thats fast enough!"  It seems the 6.8 crowd just keep pushing and pushing.  JMO so dont flame me.  Just curious is all
Link Posted: 11/25/2008 8:01:50 PM EST
[#20]
Quoted:
Quoted:
Quoted:

The most salient point which should be taken from this is that the 6.8 SPC is so efficient, that it can burn enough of its powder charge in very short barrels, to generate some striking velocities.  Thus, you can go to the 11.5, 12.5 or 14.5 inch barrel without giving up a huge amount of terminal performance, as has been the criticism of the 5.56mm (such as M855) when fired out of the 14.5" M4 versus the 20" M16.  




Every cartridge burns its powder in the first few inches of barrel. It has nothing to do with efficiency.


Not true, otherwise you wouldn't get fireballs from mosins, bmg or my friend's carbon15.


Umm the fireball is the hot gas coming out of the barrel. Not burning powder. It glows because it's hot not because it's still burning.
Link Posted: 11/25/2008 10:12:44 PM EST
[#21]
320pf,

I am not overly impressed with the inelastic test media used in the photo you posted from the Aaron Carter article, as it has no correlation to results in living tissue.

The SSA 85 gr Barnes TSX loading is most impressive and offers outstanding terminal performance:

Link Posted: 11/25/2008 10:13:38 PM EST
[#22]
320pf,

I am not overly impressed with the inelastic test media used in the photo you posted from the Aaron Carter article, as it has no correlation to results in living tissue.

Forest,

The SSA 85 gr Barnes TSX loading is most impressive and offers outstanding terminal performance, especially for 16" and under barrels:

Link Posted: 11/26/2008 1:47:36 AM EST
[#23]
Kind of my point. At what velocities do you go " OK thats fast enough!" It seems the 6.8 crowd just keep pushing and pushing. JMO so dont flame me. Just curious is all



I agree, it seems as though the 7.62x39, 6.5g and even the .223 guy's are content with the realization that their cartridges are mid power assault rifle chamberings in the most classic sense of the term and are willing to accept the limitations such cartridges represent

But the 6.8 guy's don't seem as though they'll be content till they either match .308 based cartridges performance or blow a rifle plum the hell up trying....WHY?

I don't know about ya'll but if I need to put a hole in something 400m away I'll just reach inside the safe and pull out a bolt gun chambered for a full powered rifle cartridge
Link Posted: 11/26/2008 2:15:22 AM EST
[#24]
Quoted:
320pf,

I am not overly impressed with the inelastic test media used in the photo you posted from the Aaron Carter article, as it has no correlation to results in living tissue.

Forest,

The SSA 85 gr Barnes TSX loading is most impressive and offers outstanding terminal performance, especially for 16" and under barrels:

http://i459.photobucket.com/albums/qq319/DocGKR/85grTSX10ft.jpg?t=1227687102


DocGKR:  Need to know at what velocity, and from what barrel that gel was hit –– if you don't mind...

I'm looking to do an SBR deer/antelope gun and the 85gr TSX looks like a 6lb wonder gun in that role.

Thanks.

Link Posted: 11/26/2008 2:15:58 AM EST
[#25]
Quoted:I don't know about ya'll but if I need to put a hole in something 400m away I'll just reach inside the safe and pull out a bolt gun chambered for a full powered rifle cartridge


...then I guess we'll see you later.

Link Posted: 11/26/2008 4:56:05 AM EST
[#26]
So just for a comparison, What is the difference in pressure between a 5.56, 6.5g, and 6.8spc in the hotter loads.  I would just like to know for all of the posts lately saying how all of us 6.8 shooters are going to blow ourselves up.  

And do you think we could get that fps up to 3500?
Link Posted: 11/26/2008 5:16:47 AM EST
[#27]
Link Posted: 11/26/2008 5:35:23 AM EST
[#28]
Some of you 6.8 plunderers ( I am excluding Forest, he's not one of them) never cease to amaze me.

If you go back and read the 6.8 performance test (and I know it greatly pains some of you to actually wade through FACTS and scientifically complied data to support our work ) then you will see that this is what we are doing / have done:

If you take a max pressure of 55,000 PSI (and we think it should be closer to 58,000 since we have fired hundreds of rounds at this level with no advers effects) then there will be certain limitations to velocity for a given load.

If you use the 1 X 10, 6 groove and tight chamber, then you can only get X velocity from each cartridge.

If you use a longer chamber, slower twist and shallower and fewer lands, then you can acutally get x + 100-200 FPS AT THE SAME PRESSURE!!  

It is getting a bit tiring to have to repeat this ad nauseam.

If we can better this round WHY THE HELL WOULDN'T WE DO THAT?  When it was released, it could not do the things you have seen done in the last 2 years.

It is just that simple.  The .277 never was supplied in GOOD BULLETS.  Just getting better bullets, i.e those with better terminal effx, BC. SD, etc is part of it.

Getting better guns and loads completes the circle.

Micro rant off....
Link Posted: 11/26/2008 6:22:45 AM EST
[#29]
DocGKR,

I have to agree with what SHIVAN said.  The photos of the ballistic gel tests that you posted are not very useful without any information on the test conditions, particularly the bullet velocity data.  

I agree that the test media that was used in the Carter article does not simulate tissue as well as ballistic gel as far as wound analysis.  With that said however, it does simulate tissue well enough to test bullet deformation at various velocities.  Moreover, to say that there is "no correlation" to results in living tissue is a bit overstated.  The test media used does give an first order approximation of the wounding potential of a particular bullet at a particular velocity.  

Is the test media as good as ballistic gel? NO! But it is a lot easier to use and store.  Moreover, it is a lot less expensive than ballistic gel and gives that shooter a reasonably good idea of how his particular load will perform. Also it is reusable.  

With that being said, what is to debate here?  I simply stated in my original post that the Barnes bullet should:

"preform very well out to about 200 yrds."

I then went on to say:

"Basically the design of Barnes bullets is such that they start behaving like solids once the velocity drops below ~2000 fps. Here is a photo from the article showing the Barnes bullet performance."

Do you have any data that contradicts this statement? Unfortunately, the photo of the ballistic gel test that you posted is pretty much worthless without the bullet velocity information.  

Respectfully,

320pf
Link Posted: 11/26/2008 7:11:39 AM EST
[#30]
16" 1/10 barrel, 3099 fps MV, block at 10 feet.  FWIW, the results are nearly identical when tested at 100 yards...

For civilian hunting, a 55K pressure is probably OK; for military use, 50-52K is a better way to go.  Here is what Cris Murray, a designer of 6.8 mm and 7x46 mm, wrote recently about the pressures in the two cartridges he has helped birth:

""Pressures must be kept below 52K or during a fight your rifle will be usless after the second magazine.  True, during slow fire you can push the pressures up, the Army's long range 5.56 match load is a 90 gr projectile over 60K, but its slow fire-single loaded for 1000yd matches only.  The old 1000yd, 180 gr 7.62 match load would literally melt down a M14 if you could've loaded them in a magazine and shot them for rapid fire.  This is the one reason I restarted worked on the 7x46UAC, because it allows excellent ballistics without 52K+ pressures that would render it usless in a real fight.  I've got factory made 7x46mm brass from Privi Partizan.  Their brass is made straight from long 7.62x39 blank cartridge case they make and has the nice thick Russian rim, I want.  Hopefully I'll be able to finish the pressure and powder tests this time, I'm trying to keep the speed at 2650 fps with a 130 gr projectile with pressure below 50K; all this out of a 16.5in barrel.  The last tests were good, but I need to document them with telemetry."
Link Posted: 11/26/2008 7:50:00 AM EST
[#31]
If you take a max pressure of 55,000 PSI (and we think it should be closer to 58,000 since we have fired hundreds of rounds at this level with no advers effects) then there will be certain limitations to velocity for a given load.

If you use the 1 X 10, 6 groove and tight chamber, then you can only get X velocity from each cartridge.

If you use a longer chamber, slower twist and shallower and fewer lands, then you can acutally get x + 100-200 FPS AT THE SAME PRESSURE!!


OK one simple question then?

Why don't you take this technology and apply it to other cartridges?
Link Posted: 11/26/2008 7:53:18 AM EST
[#32]
I have built 3 6.8s and have put up the chrono. It kills and kills well with just about any load. These are pictures of the Barnes 110 gr TSX (old style) taken out of a 350ish lb black bear (lodged in far shoulder)I took in June with my 6.8 The load was 30.5gr of H335. The shot 103 yards. Estimated fps 2800. Just thought people would like to see it does open up in real world hunting.








Link Posted: 11/26/2008 8:11:02 AM EST
[#33]
Quoted:
If you take a max pressure of 55,000 PSI (and we think it should be closer to 58,000 since we have fired hundreds of rounds at this level with no advers effects) then there will be certain limitations to velocity for a given load.

If you use the 1 X 10, 6 groove and tight chamber, then you can only get X velocity from each cartridge.

If you use a longer chamber, slower twist and shallower and fewer lands, then you can acutally get x + 100-200 FPS AT THE SAME PRESSURE!!


OK one simple question then?

Why don't you take this technology and apply it to other cartridges?


The other cartridges have been around for a while, and the chamber has been standardized and groves adn twists are all pretty well known.  In other words, there is not much room to play with.  However handloaders are constantly tweaking with better bullets and powders.  Bullet selection with both 223 and 308 bullets is far better than in the 270 class.  

The 5.56 has come along way recently with heavy bullets, like the 75 and 77 grain loads.   The .308 is well known with bullets in the 168-175 range with twists of 1:12 or 1:10.  There has been some advancement with VLD bullets and interesting twists like the Mike Rock 5R barrels.  So while there have been advancements with other cartridges, they are not as dramatic as what we see with the 6.8.

Since the 6.8 is newish and is NOT of government background, it was not fully optimized.  When introduced, the available bullets were meant for 270 winchester:  big and heavy.  It did alright with those constraints.  The longer, heavier bullets lead to fast twists barrels.  

Now more lighter bullets are becoming available.  As the bullet weight goes down, the twist can get slower, and so velocity goes higher.

There are many pieces of the puzzle, and many ways to put them together.  Its in our nature to try to find the best.
Link Posted: 11/26/2008 9:54:53 AM EST
[#34]
Link Posted: 11/26/2008 10:13:04 AM EST
[#35]
Quoted:
Quoted:
If you use a longer chamber, slower twist and shallower and fewer lands, then you can acutally get x + 100-200 FPS AT THE SAME PRESSURE!!  


Agreed which is why I'm running my 110gr VMAXes in such a beast..

I'm just curious why we're maxing out the velocity on a low BC non armor piercing bullet, instead of one with a highe BC (like the 110gr TSX or the 110gr VAX with a BC in the range of .360-.370)?  


That's what I've been driving at? Why all this emphasis on velocity velocity velocity with projectiles with poor BC and SD's. Time and time again with just about every cartridge under the sun higher BC at moderate velocity trumps low BC at high velocity at range.

Some of it may be that the 6.8 case is simply too long allowing no upward mobility in the bullet weight spectrum so the only way to go is down. To that end I can understand opening up the twist rate. Why bother with a 1-10" twist when 110grn bullets are all that'll fit in the mag

What is this 85grn bullet good for? What does it do that 110grn projectiles won't? I think the answer is simply that speed sells.
Link Posted: 11/26/2008 10:40:16 AM EST
[#36]
I hope you are kidding...what is this 85 gr load good for?  How about meeting the required terminal performance guidelines while being relatively barrier blind, as well as lead free.

 

“Barrier Blind” ammunition should demonstrate minimal changes in terminal performance between unobstructed shots into bare gelatin and those obstructed by intermediate barriers.
Link Posted: 11/26/2008 10:46:24 AM EST
[#37]

I hope you are kidding...what is this 85 gr load good for? How about meeting the required terminal performance guidelines while being relatively barrier blind, as well as lead free.



I hope you're kidding? You guys come up with the most off the wall high speed low drag "criteria" for this sporting cartridge[>:/]

and this does what in the real world vs other 100% copper bullet loads? Are you saying that any living thing, target or piece of equipment will be any deader because this load was used. Are you saying that a 115grn loading won't meet these "critera"

Gimmie a Break,  Fewer Tom Clancy novels and more range time would do this forum good.

Link Posted: 11/26/2008 10:55:06 AM EST
[#38]
Link Posted: 11/26/2008 11:01:05 AM EST
[#39]
Link Posted: 11/26/2008 11:04:50 AM EST
[#40]
Umm you realize this 'sporting cartridge' was initialially developed BY military members for Military use, we sporting guys just sorta latched on.


and how far did that get?  Has anyone anywhere in the world been shot in anger with a 6.8spc?


I'm done with this thread, I started out being respectfull trying to ask legit questions and discuss ballistics but as usual I just get the same flames the 6.8 clique always dishes out to us non believers.
Link Posted: 11/26/2008 11:08:28 AM EST
[#41]
Quoted:
Umm you realize this 'sporting cartridge' was initialially developed BY military members for Military use, we sporting guys just sorta latched on.


and how far did that get?  Has anyone anywhere in the world been shot in anger with a 6.8spc?


Why are you so against everything it is done w/or by this cartridge?  I really am curious.  What is the issue here?
Link Posted: 11/26/2008 11:11:28 AM EST
[#42]
Quoted:
Quoted:
Umm you realize this 'sporting cartridge' was initialially developed BY military members for Military use, we sporting guys just sorta latched on.


and how far did that get?  Has anyone anywhere in the world been shot in anger with a 6.8spc?


Why are you so against everything it is done w/or by this cartridge?  I really am curious.  What is the issue here?


What am I against? The only thing I wanted to know is why the push to lighter and lighter projectiles for what appears to be the sake of velocity alone. Why is the 6.8 crowd so damn sensitive about such matters

Link Posted: 11/26/2008 11:17:54 AM EST
[#43]
Link Posted: 11/26/2008 11:28:18 AM EST
[#44]
Quoted:
Quoted:
Quoted:
Umm you realize this 'sporting cartridge' was initialially developed BY military members for Military use, we sporting guys just sorta latched on.


and how far did that get?  Has anyone anywhere in the world been shot in anger with a 6.8spc?


Why are you so against everything it is done w/or by this cartridge?  I really am curious.  What is the issue here?


What am I against? The only thing I wanted to know is why the push to lighter and lighter projectiles for what appears to be the sake of velocity alone. Why is the 6.8 crowd so damn sensitive about such matters



Well then, IMHO, they seem to be experimenting to see what it is capable of correct?  The 85gr is a new bullet offering, so they don't know.  They are testing what it is capable of.  They've already tried w/the older bullets, so now it's the 85's turn.  What is the harm in that?  Would you rather have an 85gr bullet traveling at 3000fps or 2600fps?  Easy answer for me, anyway.  Why wouldn't you want it traveling at the fastest safest speed possible.  Why? What do you gain by having traveling slower?  What?  From the post earlier, it looks as if the 85 doesn't perform as well under 2000fps, so by upping the fps, wouldn't you be increasing the range of it's performance?  They're setting the standards for the 6.8spc.  If the BC was the end all wouldn't be only shooting 77gr in 5.56 and 175-180's in the .308?  They don't seem sensitive to me either, they've answered all of your questions to the best of their knowledge from what I've read.
Link Posted: 11/26/2008 11:32:19 AM EST
[#45]
Quoted:What is this 85grn bullet good for?


I'm going to use it to whack quadripeds in various species.  I don't give a shit what JSOC, or anyone else, uses it for...
Link Posted: 11/26/2008 11:41:22 AM EST
[#46]
+1  Tomorrow will my first hunting trip w/mine.  Hopefully, it will be a great weekend.
Link Posted: 11/26/2008 11:54:45 AM EST
[#47]
Quoted:
Quoted:
Quoted:
Umm you realize this 'sporting cartridge' was initialially developed BY military members for Military use, we sporting guys just sorta latched on.


and how far did that get?  Has anyone anywhere in the world been shot in anger with a 6.8spc?


Why are you so against everything it is done w/or by this cartridge?  I really am curious.  What is the issue here?


What am I against? The only thing I wanted to know is why the push to lighter and lighter projectiles for what appears to be the sake of velocity alone. Why is the 6.8 crowd so damn sensitive about such matters





SENSITIVE??  You, sir are the one that I see came here to wonder about why the "6.8 crowd"  would do something as hideous and illogical as to shun mediocrity.  Then, you turn around, when the answer doesn't make you look like you know what you are talking about, and you say "I'm done with this thread...?"

Who the hell is sensitive here?  And why do you constantly argue that there is no reason whatsoever to push a Barnes TSX a little faster?  Have you ever shot an animal with these bullets?  Just wondering.

You are showing some ignorance.  You push the Barnes bullet faster because:

1) it expands more at higher velocities
2) that expansion can take place at longer ranges if the muzzle velocity is substantially greater than a TSX of heavier mass.  BC has little effect on tissue.  However, I never said a word about "long range..."
3) the Barnes TSX has NO LEAD in it, and if you pay attention to political trends, there may be an attempt to ban lead containing projectiles.  These will survive that.
4) the lighter bullet allows for less pressure in the guns that are still using "old" 6.8 SPC specs....moreover, the gas rings have always allowed for a lower pressure load.  This bullet is among those with the lowest pressure, and highest velocity, so it is safer in those guns, like the DPMS, which tend to cause higher pressure with their extremely tight chambers.  I suppose you think we should be striving for higher pressure, less velocity?
5) there aren't any other bullets (curently available for the 6.8 SPC) which perform like the copper monolithic Barnes TSX and TTSX (and the GS custom from S Africa).  I know because I have fired and tested every single one, including many which are not designed for 6.8, rather .270Win. (Winchester Ballistic Silvertip, Sierra Game King, Barns 120 solid, and on and on)

You know, sometimes I think you come to these threads just to throw mud.  I hope that you are done with it.  Then, we can get on with a civil discussion about the test I posted, simply to report that the velocity was as advertised by SSA....NOT to announce a drag race.

These rounds are factory loadings.  THEY ARE NOT WILDCATS!  So, please get off the notion that we are simply pushing things to the limit just to push them.  They are the products of an evolution.  

And, ummmm, Doc GKR isn't a regular sporstman, reloader or "enthusiast."  You might want to look up his credentials before you start to argue these points with him....just sayin'
Link Posted: 11/26/2008 11:56:11 AM EST
[#48]
Quoted:
Quoted:
If you take a max pressure of 55,000 PSI (and we think it should be closer to 58,000 since we have fired hundreds of rounds at this level with no advers effects) then there will be certain limitations to velocity for a given load.

If you use the 1 X 10, 6 groove and tight chamber, then you can only get X velocity from each cartridge.

If you use a longer chamber, slower twist and shallower and fewer lands, then you can acutally get x + 100-200 FPS AT THE SAME PRESSURE!!


OK one simple question then?

Why don't you take this technology and apply it to other cartridges?


The other cartridges have been around for a while, and the chamber has been standardized and groves adn twists are all pretty well known.  In other words, there is not much room to play with.  However handloaders are constantly tweaking with better bullets and powders.  Bullet selection with both 223 and 308 bullets is far better than in the 270 class.  

The 5.56 has come along way recently with heavy bullets, like the 75 and 77 grain loads.   The .308 is well known with bullets in the 168-175 range with twists of 1:12 or 1:10.  There has been some advancement with VLD bullets and interesting twists like the Mike Rock 5R barrels.  So while there have been advancements with other cartridges, they are not as dramatic as what we see with the 6.8.

Since the 6.8 is newish and is NOT of government background, it was not fully optimized.  When introduced, the available bullets were meant for 270 winchester:  big and heavy.  It did alright with those constraints.  The longer, heavier bullets lead to fast twists barrels.  

Now more lighter bullets are becoming available.  As the bullet weight goes down, the twist can get slower, and so velocity goes higher.

There are many pieces of the puzzle, and many ways to put them together.  Its in our nature to try to find the best.




+ 100.  I probably could not have said it any better.
Link Posted: 11/26/2008 12:09:39 PM EST
[#49]
Quoted:
Kind of my point. At what velocities do you go " OK thats fast enough!" It seems the 6.8 crowd just keep pushing and pushing. JMO so dont flame me. Just curious is all



I agree, it seems as though the 7.62x39, 6.5g and even the .223 guy's are content with the realization that their cartridges are mid power assault rifle chamberings in the most classic sense of the term and are willing to accept the limitations such cartridges represent

But the 6.8 guy's don't seem as though they'll be content till they either match .308 based cartridges performance or blow a rifle plum the hell up trying....WHY?

I don't know about ya'll but if I need to put a hole in something 400m away I'll just reach inside the safe and pull out a bolt gun chambered for a full powered rifle cartridge



Your posts would be much more highly respected if you did not spew such tripe as this.

You said you came here to simply discuss ballistics....uhhh....riggghhhtt.  Our research is designed to optimize the 6.8 for what it is, and to help prevent people from doing exactly that...blowing up rifles.  Since there are so many different barrel designs on the market, such as Model 1 sales barrels with SAAMI chamber and 1 in 9.5" twist, and the DPMS, with its ridiculously tight chamber, we have been forced to inform people that these guns are not safe testing platforms, when developing 6.8 handloads ....especially if they happened to use the old extreme bullet.

I happen to own a .308, and know full well where that cartridge's capabilities transcend that of the 6.8.  But, ummm, you see, I don't own any 5.75 lb .308 rifles with 12.5 inch barrels, that still produce 80% of the cartridge's full velocity potential, much less recoil, and without a 3 foot flame coming out the end.

Link Posted: 11/26/2008 12:29:06 PM EST
[#50]
Forest,

Think short barrel weapons.  Also, the 110 gr TSX generally penetrates beyond 20"––much deeper than the FBI recommended 12-18" distance; for situations where you want the projectile to remain in the target, the 85 gr load is far superior.  For hunting larger game, say 250-300 lbs and up, the 110 gr TSX is likely a better choice.  Having variety is good!
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