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Eh, I viewed this thread being more for a guy interested in 6.8 more so than the companies. Don't get me wrong, those companies who did participate are owed recognition and consideration for doing so. But I wouldnt say that because a company didnt participate means they shouldnt be in the running. We've had a couple in where I work and the RRA looks like a good gun. |
I've sent everyone who asked for their uppers back, but still have several here. I'll if they are ok with my selling them, and if so, what they would like out of them. If any of you are interested in getting one of these uppers, let me know. I'll see if I cant make it happen. If anyone is interested, I can send the test targets with them!  Whats still here: MSTN - $1600 JTAC - $1000 Denny's - $1200 LWRC LMT Stag - $400 AR15barrels.com |
It could possibly mean Southern Gun Company, a UK based AR manufacturer who does export some things to the US. |
Really? Learn something new everyday! Mike |
If anyone is interested in my upper, NAG can send it back here for a new LMT Bolt Carrier, cleaning and once over before it ships to the customer. Jason |
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Great report...lots of information. So I'll like to get one?? Which would you buy for Deer/Elk/Moose hunting? I live in Alaska... we have small deer and big moose. I have a RRA 223/5.56... would like to get a upper at 6.8. Also can you post links to each uppers manufacturer. Thanks for all your hard work. I know you love shooting the test... it's more fun then work. |
| There are links on page one to all of the manufacturers. Which you should buy is very subjective. Stag is clearly the cheapest, but the KoTonics is probably the best value. However, Denny and JTAC's upper are priced very competitively for the quality of the build and parts used. The MSTN upper was the most consistent and controlable to shoot, they spared no expense in the build and the price tag reflects this... so did their results. I feel like Im jsut repeating myaself here... read the report, read the replies. Pick one you find peaks your interest. I doubt you will be disapointed. |
Reno, Please also remember that if the upper has a 1 in 10" twist, there is a greater likelihood that you will see excessive pressure signs if you shoot higher velocity reloads or SSA combat pressure ammo in that upper. This is even more of a problem if there is also a SAAMI chamber. If you are going after moose or Elk, I would definitely recommend that you get the upper that affords your cartridge the absolute highest performance, including velocity. How is this accomplished? What I strongly recommend for new 6.8 buyers is that they get any upper that has the SPCII or DMR chamber and 1 in 11" twist. There are currently only two on the market with these two features (which may give an extra 100-200 FPS, when SSA combat loads or hot reloads are used). 1) Ko Tonics KT 68 upper has 1 in 11" twist and SPC II chamber. It is the only upper on the market with both pressure reducing features. 2) AR15performance (not tested) also custom makes a 1 in 11" twist with DMR chamber (just a little bit longer than SAAMI but not as long as SPCII) and it, too will shoot the fastest loads. 3) guns with SAAMI chamber and 1 in 11" twist are capable of shooting the above mentioned loads, but if the bullet is loaded long, it will touch the lands. With some bullets, this can be good for accuracy, but sometimes it will result in increased pressure, which is why I favor the combination of SPCII chamber and 1 in 11" twist. I am doing a write-up on an ammo test done last weekend with Art Kalwas of SSA and Constructor, regarding this very issue soon, in the variants forum. We hope to answer some of these questions for those just getting into 6.8. Watch for it as early as next week. hope this helps  |
True in 16 inch brls and longer... the shorter brls (from what I hear) can have the 1/11 because they r under pressure for a shorter time Mike |
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My barrels have never had a problem with SSA ammo. I would like to see chrono data included. Elk and Moose are beyond the envelope for 6.8 no matter what the loading. Please feel free to borrow my upper from the F;prida boys if you would ;like to include it in your tests. |
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These uppers are for sale here www.ar15.com/forums/topic.html?b=7&f=119&t=516376 |
Mike, www.ar15.com/forums/topic.html?b=3&f=121&t=369145 Sorry to get this link up so late, but I am sure most of you have seen it by now. I have received Denny's upper and am excited about testing it (with Chrono data, of course) and others on the way. Thanks Neil and Denny!! I didn't mention brands in the first test, because I didn't have permission to do so, but lately, MFR's are offering their barrels for testing. This is a great thing, because I think they sincerely want to know if the 10 twist is really the issue we are making it out to be. I think we have presented ourselves as objective, and I want the truth found in as scientific a manner as is possible. I welcome any help they or other industry professionals can offer us in this testing. I have no financial interest or axe to grind. Now for my opinion: The SAAMI chamber is all but dead, as almost every single MFR has switched over to the SPCII now. That bug is all but fixed and MFR's convinced. Now, if we can just convince them to upgrade the twist rates to 11 and 12, you should see the 6.8 SPC gain 100-200 FPS velocity across the board, and most of the previous pressure problems seen early on will disappear. I believe this is analogous to the .223 versus 5.56 chamber issue during that round's development. I can't wait for the day we don't have to hear "but, but...will it shoot SSA combat loads...?"   |
That will happen the week after the questions regarding M-4 feed ramps stops, which will happen the week after the question "Did Mattel make M-16's" stop. |
That is "magically delicious" to know, Vic.  Thanks to all the folks who let their uppers participate in the testing, and hat's off to our lead tester and all associate testers! And as to this:
I had always figured our lead tester abbreviated as "NARG," but this is good to know. 
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Indeed!
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I was thinking the same, but check the pics, the upper they sent used a carbine length gas system. More recent MRP's I have seen also use the mid though. |
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SSA makes what you call "Milspec" ammo. It is the SSA Combat line and if you use the SPCII chamber you can use it and will get 100-120 FPS increase at the same pressure that a SAAMI chamber 1:10 gets with the commercial ammo. Most of the makers now use the SPCII chamber. The chamber that was tested by th 5th group and all the data was from had the lead of the SPCII. Remington in typical fashion turned it into a custerf7ck by chopping the throat length in half right before sending it to SAAMI. This could have been because they only fielded a bolt gun at the time or that they had already lost the contract on the production to SSA because they could not meet the mils specs so it was sour grapes and they were trying to castrate the round performance wise. Their ammo certainly is the worst stuff I have ever seen. Surplus 7.62x39 is more accurate in a shot out AK barrel.
Even the companies that have in the face of all the data collected for the last 3 years held that the the chamber and twist make no difference are now changing there tune. Even if you only choose to shoot the lower power ammo if you use the proper specs it will be operating at a lower pressure and give you higher vel so you will still get more performance and decreased wear on top of that from the lower pressure. There is such a overwhelming amount of data that proves the increase performance a longer lead chamber and a slower twist rate of 1:11-12 creates companies not changing are seeing their sales drop compared to those offering the correct specs. It is the same as the SAAMi .223 vs 5.56 chamber. You blow primers in a .223 where the only real dif is the throat length If you are interested in the most current and accurate info on the 6.8 I suggest you try the 6.8 Forums Site You do have to register to view as it put in place to prevent all spam and bots out there but has by far the largest collection of data on the 6.8 |
| As far as an SPR type build in mind, has anyone determined what bbl length is the best, efficient, compromise for the 6.8? I see a lot on this test were 16". Would 18" offer that much more? Would it be a waste to even consider the 12" for CQC compared to the 5.56 or worth the extra energy? |
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The 18" will get you 50-70 FPS more vel going to a 20" will add another 35-50. With SSA loads its a bit less then that as they use a faster powder that delivers most of its speed in under 16".
For an SBR. That is the entire reason the 6.8 was created in the first place.The 5.56 lost too much punch in SBRs. The 6.8 looses less and has a lot more punch in SBRs. The 6.8 works great in SBRs from 12.5 to 8". The 12.5 is a great length, IMO, as it allows the use of reflexed suppressors with the carbine port location. It is also the softest shooting of the SBR lengths. People with the 12.5 with SPCII and 11 twist are getting 2400 fps from the 115 OTMs which I think is very good. There are some threads on 6.8forums about it and reviews. One member with a 10" upper has used it for a number of hunting seasons to take deer out to 300 yards so I think it has more then enough punch. Personally I really like the 12.5 inch setup as it gives the most versatility and gives the most punch while still being very handy. Also when a reflex like the Ops, Surefire ect is added its still only 16" long. If without a suppressor as a concern then a 11.5 is quite nice. The 6.8 has less pressure then the 5.56 at any of the port locations compared to the 5.56 so its easier on the parts. At any length the 6.8 will offer a significant increase in performance over the 5.56 and the SBR lengths even more so. The great thing with the 6.8 is th efficiency of the cartidge. Even at 8" is burns 90-99% of the powder before the muzzle depending on the load. Most cartridges at this length would be flame throwers. At 13" just about every powder typically used for the 6.8 will burn 99%+. The SSA loads are specifically made to burn completley in the shortest length possible in balance with getting the best velocity. |
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Quoted:Personally I really like the 12.5 inch setup as it gives the most versatility and gives the most punch while still being very handy.
Who sells the barrels and headspaced bolts in the SPCII chamber and 12.5" SS and 18" SS? While I'd like to help Cardinal Armory out, I don't want to risk getting a "bad barrel". Advise... |
| AR15Performance will give you it exactly as you want and is not as $$ as others offering the same quality. WOA now does, You will have to check with Denny's but the last Recon we checked from him had a SPCII chamber. Since they both get their barrels from Compass Lake and are the same Wilson blanks it makes sense. Here is one I am sure you will like. Noveske is in the process of changing his specs and due to release in the next month and they will have the slower twist and long lead chamber. |
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Quoted:
anyone know anything about ko-tonics webiste. it doesnt seem to work anymore? or is there another dealer that distributes their products? They changed their name awhile back to Cardinal Armory. Now they are going out of business. Here is a link to their Industry Forum here on AR15.com http://www.ar15.com/forums/forum.html?b=2&f=234 And here is a link to their web site... http://cardinalarmory.com/cardarm-pcart/pc/viewContent.asp?idpage=14 It's official. Cardinal Armory is in the last stages of going out-of-business.
Why? Without a large outside investment, we couldn't reach the volume of sales that we needed. We were profitable, but not enough so that I could pay my mortage and put food on the table. Thankfully, we have been able to pay off 100% of business debt. Providing for the family is first priority, so I have a new more-than-full-time job. I don't have time to give out free 6.8mm SPC advice, please go to http://www.68forums.com for that. We aren't doing "special orders," and we are pretty much out barrels. Sorry. If you purchased one of our barrels from ANY source and it is exhibiting pressure signs when firing high-pressure rounds, please send an email and I will try to help. Just understand that I do this strictly as a spare time activity, and I don't have much time to spare. About the only thing I might be able to do is ream and polish the chamber. All barrels and uppers purchased after June 2008 already have their chambers reamed and polished, so if you bought a barrel after that time, there may be little more that I can do. Thank you so much for all the encouraging emails and phone calls when we were beginning to have troubles. You are the greatest customers a small business guy could ever want. - Tim FB |
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Quoted:
The bolt came with a standard power extractor spring and blue insert. The exterior of the extractor was marked SGC? Anyone know what that means? I am a big sci-fi fan so when I saw SGC all I could think of was Stargate Command. Good work. I like Noveske's rifles, but in my mind I can't see paying that money for a DI set up. I know he has done testing with DI vs piston guns and found no real advantages but I know how dirty DI rifles get, especially after doing a little TAD as a Marine Corps Armorer. |
Meh, most all of these uppers were expensive. Some a little more so than others, but at the end of the spectrum the majority of these guns were running, price would not be a deterrant. DI guns get dirty, but in my (limited) experience, they continue to run if kept wet. I've run some classes 100% silenced. Talk about a dirty gun. I kept them wet; they kept running. I like pistons, really. I have a couple. But its hard for me to jump on the piston revolution band wagon when all of my (good quality) DI guns have run so well. 
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I was looking at your chart, and for the MRP you have carbine gas system. I'm 99.9% sure that the CQB uses a Mid Length gas system. Great read. The 16 inch CL and the 18 inch SS 6.8 barrels both have carbine gas tubes. Only the 16 and 18 inch 5.56 barrels have the mid length gas tubes. 
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Hello, I am new to this page and just put together my first BushMaster AR-15 today. It is an A3M4 config and I really like it. I have a extra A2 upper from my purchases and would like to put together a 6.8. Is it OK to use the A2 upper with the 6.8 barrel and bolt, will they fit????
This looks like a great site, I'm looking forward to building another rifle soon.......... NavyNuke |
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Hello, I am new to this page and just put together my first BushMaster AR-15 today. It is an A3M4 config and I really like it. I have a extra A2 upper from my purchases and would like to put together a 6.8. Is it OK to use the A2 upper with the 6.8 barrel and bolt, will they fit????
This looks like a great site, I'm looking forward to building another rifle soon.......... NavyNuke |
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