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Thread: New 6.8 mm and .300 BLK tests

  1. #31
    Site Supporter PearTree's Avatar
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    Quote Originally Posted by DocGKR View Post
    The 110 gr GMX works very well and is certainly acceptable for .300 BLK duty use.
    I may have missed it, but do you have a list of doc approved .300 BLK? I didn't see it stickied and last I remember you said no current ammunition was suitable for duty use. I and some of my co-workers are kicking around the idea of a duty .300 BLK sbr.
    Last edited by PearTree; 10-16-2017 at 04:10 PM.

  2. #32
    Site Supporter DocGKR's Avatar
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    Right now the best are likely to be 110 gr GMX and 110 gr TTSX.
    Facts matter...Feelings Can Lie

  3. #33
    Site Supporter PearTree's Avatar
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    Do you still advocate a proper 5.56 with quality ammunition over .300 BLK? Or is the ammo you mentioned reached a level of performance where the .300 BLK is now a viable option for LE?

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  4. #34
    Site Supporter Sensei's Avatar
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    Certainly not Doc, but the Barnes TTSX and especially this GMX appear to offer noticeably better gel performance than anything the 5.56 offers when shot from barrels <11.5 inches. That includes the newer all copper 5.56 rounds that do pretty good from sub-11.5” barrels. That GMX load seems to open up beautifully and penetrate just out to 18” after safety glass and metal barriers.

    I’m at the point now where the only thing keeping me from always using a 300blk SBR is ammo availability. When traveling far away from home or resupply, I’m using a 5.56 SBR. Otherwise, it’s 300blk for me when within driving distance of my stash.
    I like my rifles like my women - short, light, fast, brown, and suppressed.

  5. #35
    Anything new in the land of 6.8 worth mentioning?

  6. #36
    I've been playing with an AR wildcat called the 277 Wolverine. It is similar to the 300BLK and 7.62X40 and is based off the 223Rem case but uses 6.8/.277 bullets. It can be loaded to supersonic or subsonic velocities and I've had no problem getting a 150gr bullet to cycle subsonic suppressed.

    I've been quite pleased with two bullets when loaded to supersonic speeds. These are the Nosler 90gr bonded and the Speer 90gr Gold Dot. I can push these to about 2,400fps from a 12.5" barrel and am getting 16-18" of penetration in my block of 10% gel from Clear Ballistics. Guys running 16" or 18" barrels have reported muzzle velocities closer to 2,600-2,700fps with the 90gr bullets.

    The down side to both the Nosler and the Speer is price. They're expensive and the Gold Dot can be hard to find. But Starline is now making brass for the 277WLV and Speer is supposed to be working with a commercial loader/reloader to provide Gold Dots for "factory" ammo.

    Photos of 90gr Gold Dot recovered from gel.

    Last edited by Tokarev; 11-14-2017 at 04:49 PM.

  7. #37
    If for no other reason, the 90gr Gold Dot 277WLV info should be useful for guessing terminal performance of the 6.8 at longer range.

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  8. #38
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    Quote Originally Posted by Tokarev View Post
    If for no other reason, the 90gr Gold Dot 277WLV info should be useful for guessing terminal performance of the 6.8 at longer range.

    Sent from my SM-G930P using Tapatalk
    I love the idea of the 277 Wolverine. I happen to have a 7.62x40wt and it’s great, but bullet selection is limited as well — waiting on a 105-120 grain gold dot or Nosler BSB in 30 cal.

    Question for you is, when comparing the 6.8spc and the 277W— they’re using the same projectiles— about how many inches of barrel does the 277w “cost” to get same velocities? In other words, if a 12.5” 6.8spc has a muzzle velocity of “x” with a 90gr gold dot, how long would a Wolverine barrel need to be to match that?


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  9. #39
    Quote Originally Posted by 4gallonbucket View Post
    Question for you is, when comparing the 6.8spc and the 277W— they’re using the same projectiles— about how many inches of barrel does the 277w “cost” to get same velocities? In other words, if a 12.5” 6.8spc has a muzzle velocity of “x” with a 90gr gold dot, how long would a Wolverine barrel need to be to match that?
    Gosh I don't know. We can assume that the 277 is a "better" choice as barrels get shorter since there's less powder to burn. At what point does the 6.8 peter out? Does it still provide good performance from a 12" barrel?

    Anyway, from previous loading experience, it isn't terribly difficult to push a 90gr bullet to about 3,000fps in the 6.8SPC from an 18" barrel.

    For comparison, I have seen a few people pushing 2800fps with a 90gr TNT in the Wolverine using Shooters World Blackout powder from an 18" barrel. I haven't used SW Blackout powder nor do I have an 18" barrel so I haven't personally verified. But that's pretty darned impressive if true.


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    Last edited by Tokarev; 11-15-2017 at 02:10 PM.

  10. #40
    I found this old thread over on 6.8 Forum with some 12.5" and 16" chrono data.

    http://68forums.com/forums/showthread.php?12231-SSA-Ammo-Chrono-Data-16-quot-amp-12.5-quot

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