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Thread: Federal 6.8 SPC ammo specific revealed.

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    Federal 6.8 SPC ammo specific revealed.

    Average muzzle velocity for this load from the 8.5-inch barrel measured a respectable 2450 fps. In doing so, this load generates 1199 foot-pounds of energy at the muzzle. Firing the same load from a 16-inch barrel produces 2900 fps and 1680 foot-pounds.

    Taking barrel length to 24 inches increased velocity to 3050 fps and energy to 1858 foot-pounds. Testing in extreme temperatures showed velocity to average 2275 fps at -29 degrees F and 2475 fps at 125 degrees F from the 8.5-inch barrel. When fired from a 24-inch test barrel, ATK recorded a group measuring 1.56 inches at 200 yards.
    Source

    At 1200 ft lbs for the 8.5", it basically performs like XM193 does out of a 20".

    Its basically within a SSA tactical load, which a certain internet troll thinks is dangerous and no way would Federal loads reach that.

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    Here's a pretty good chart from TOS for velocity and barrel length:

    http://www.ar15.com/forums/t_3_121/5...udes_6_5_.html
    Last edited by FlyingHunter; 11-14-12 at 22:15. Reason: sentence structure
    Politician's Prefer Unarmed Peasants

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    Quote Originally Posted by Freedoooom View Post
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    At 1200 ft lbs for the 8.5", it basically performs like XM193 does out of a 20".

    Its basically within a SSA tactical load, which a certain internet troll thinks is dangerous and no way would Federal loads reach that.
    Tempting. However, I probably won't take the 6.8 plunge until I can get a source of free brass.
    Insert impressive resume here.

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    I've had good luck and consistent availability of brass and loaded ammo from Silver State Armory.

    Brass here:

    http://www.ssarmory.com/6.8mm_SPC.aspx
    Politician's Prefer Unarmed Peasants

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    2900 is the expected number from a 16" tube.

    Looking forward to this ammo.
    Black River Tactical
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    It was my understanding that the new LWRCI UCIW Six8 ammo wouldn't fit into a standard AR15 magazine well.

    That was why they made a totally new lower for it.


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    Quote Originally Posted by Snipe315 View Post
    It was my understanding that the new LWRCI UCIW Six8 ammo wouldn't fit into a standard AR15 magazine well.

    That was why they made a totally new lower for it.

    The problem is with all 6.8 ammo, not just the Federal UCIW Six8 ammo. 6.8 magazines generally aren't very reliable due to the larger case diameter, and they are only 20-25 rounds. The LWRC lower accepts a proprietary magazine, designed by Magpul, that features an optimized double stack configuration, but it won't fit in a standard AR15 magazine well.
    --Nick
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    Quote Originally Posted by NickB View Post
    The problem is with all 6.8 ammo, not just the Federal UCIW Six8 ammo. 6.8 magazines generally aren't very reliable due to the larger case diameter, and they are only 20-25 rounds. The LWRC lower accepts a proprietary magazine, designed by Magpul, that features an optimized double stack configuration, but it won't fit in a standard AR15 magazine well.
    The mag issue is cited in the article, and is related to full-auto fire. Per LWRC's posts on their own forum 1 magazine induced failure in 800 rds full-auto wasn't good enough. FWIW I have ~5000 rds through a 6.8 now, and have yet to have a failure (using PRI mags primarily). I don't do many mag dumps or peel drills with this round as my rifles are set up for hunting. This cartridge's appeal to me transcends the quick change AR15 upper, so I'll probably switch to the new platform.

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    Quote Originally Posted by Freedoooom View Post
    Source

    At 1200 ft lbs for the 8.5", it basically performs like XM193 does out of a 20".

    Its basically within a SSA tactical load, which a certain internet troll thinks is dangerous and no way would Federal loads reach that.
    I corrected you the last time, and you keep on misrepresenting my position. I have never said that an SSA tactical load was dangerous. Please quote me say that from anywhere on the internet.

    What I did say was that:

    5.56mm is 0.332 inches in diameter on the case head, which is 0.08657 square inches. 62,000 pounds per square inch is 5313 pounds into the bolt.

    6.8 has a case head of 0.358, which is an area of 0.10066 square inches. In order for this also to have 5313 pounds into the bolt, you need to limit it to 52,785 psi.

    To be clear - 62,000 psi for 5.56mm is the same as 52,785 psi for 6.8.

    Moreover, the 6.8 bolt is weaker than a 5.56mm bolt.

    If the 6.8 spec was raised to 58,000 psi, it would be like 5.56mm at 68,000 psi.

    If the 6.8 spec was raised to 60,000 psi, it would be like 5.56mm at 70,500 psi.

    So my point was, one cannot use 5.56mm pressure and 6.8 SPC pressure interchangeably, and so that it did not make good sense to load 6.8 over SAAMI max pressure on purpose.

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    Quote Originally Posted by Clint View Post
    2900 is the expected number from a 16" tube.

    Looking forward to this ammo.
    Remember that the round tested was the contract load that Federal is supplying and may not be introduced in 2013 commercially.

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