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Thread: Anybody still shoot 6.8?

  1. #91
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    I have (2) 6.8's. My 2005 Barrett M-468 and my ARP 12.5" SBR. I bought the 12.5 and bolt and mated it to a LaRue Stealth Upper w 7.0 rail and SLR adjustable gas block. It's shot almost exclusively suppressed .My wife has a 16" 6.8 on a LaRue Stealth upper/ LMT lower with a WOA stainless barrel and has taken two deer with it.

    12.5" on top, Barrett M-468 middle, wife's on bottom

    I'll keep my weapons,my freedom,and my money!! You can keep the CHANGE!
    Glock Certified Armorer

  2. #92
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    For a long time I had a dedicated 6.8 rifle. Sold that earlier this year, but I have parts to build an upper which I should be able to tackle pretty soon. Still got several hundred rounds of ammo, so I plan on keeping it for hunting mostly.

  3. #93
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    Quote Originally Posted by constructor View Post
    If you know what size you want the port write it in the additional comment box. I can port it any size you want it.
    My personal barrels have a .078 or .082 port but I run hot handloads and have no gas leaks. If you shoot Hornady at 54000psi and have no leaks a .082 will work. If you shoot weaker Remington and Nosler/SSA you may need a .086. If you don't seal the gas leaks and shoot Remington you may need a .089.
    I meant to thank you for this information. I see you have both 16" Scout barrels and 6.8 BCGs in stock.

    Andy

  4. #94
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    deleted
    Last edited by LDM; 09-17-20 at 13:44.

  5. #95
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    Quote Originally Posted by grizzman View Post
    It's not the latest and greatest cartridge, so all-purpose forums don't talk about it much.
    Agree, the 300, Grendel and 6.8 are all old news. The Grendel forum has never had as much traffic as the 6.8 forum has but both are pretty slow at the moment. We selling more barrels now than we ever have but not much posting going on.

  6. #96
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    You know, it's always interesting when caliber arguments come up between 6.5G and 6.8 SPC. And interestingly most people use anecdotal evidence such as "so and so shot bla bla bla at 5,000,000 yards and the deer exploded because their caliber is so much better...", you know, the moronic one liner arguments.

    Just wanted to add some actual facts to consider:

    1. Longer but smaller diameter projectiles have LESS drag while flying through the AIR (ballistic performance) than larger diameter projectiles of similar weight but also LESS drag when traveling through the TARGET (terminal performance), what favors them in preserving KE / velocity while in flight works AGAINST them when trying to actually damage the target. This FACT seems to be lost entirely in just about every argument and I never see it mentioned when comparing 6.5 G to 6.8 SPC. Bigger diameter bullets tend to expand more consistently and to larger diameters than longer skinnier bullets. But what could the US Military's elite marksmen units possibly know right? 6.5G was always intended as a target / precision cartridge with optimal trajectory favored over terminal performance. While it does outshine 5.56 NATO / .223 in terminal performance, it looses out to 6.8 SPC when actually trying to kill something despite it's slight trajectory advantage:

    https://ndiastorage.blob.core.usgovc...tl/Roberts.pdf

    https://ndiastorage.blob.core.usgovc.../Zhou19394.pdf

    http://www.frfrogspad.com/68spc.htm

    2. The inverse is true for larger diameter projectiles which shed energy / velocity more rapidly while in flight but have greater terminal performance. Case in point, the Roberts 2008 report noted that 7mm and 7.62mm provided the greatest damage to the target while 6mm and 6.5mm were more accurate. 6.8mm split the difference between the smaller more accurate calibers and the larger more destructive calibers.

    3. Both 6.5mm Grendel American Gunner OTM and 6.8mm SPC American Gunner OTM (what Hornady calls BTHP), when shot from a 16" barrel, are within spitting distance of each other by 300 yards. 6.8 SPC AG holds to 1895 FPS @ 300 yards, 6.5 G holds to 1829 FPS @ 300 yards with 6.5 G have slightly more KE when shot out of a 16" barrel according to Hornady's ballistic calculator. But velocity / KE is only PART of the overall performance, not the ONLY factor as so many arguments seem to claim. 6.8 110gr OTM (BTHP) from Hornady tends not to frag at velocities below about 1900 FPS and I would expect 123gr OMT (BTHP) to be even worse have less bearing surface area (less hydraulic pressure on impact), so both are at the limit or just beyond the reliable limit by about 250 to 300 yards at those velocities. For hunting applications...what's the freaking difference and how could one argue one is "massively better" than the other? Logically, one cannot!

    4. 6.8 SPC was designed as a military cartridge first and foremost. I saw an ignorant statement made by someone stating "there is no reason for them to use the outdated rem. 30 case with it's smaller head diameter than the 7.62x39mm parent case used in 6.5G that limits projectile length more than neccesary for 6.8" when in reality it had to do with magazine feeding reliability and bolt head durability (big issue with AR-15's in combat) which have now been proven beyond doubt. There's more to it than just long range paper target performance.....7.62 AR's are not known for good bolt reliability in an AR-15 even with 7.62's inferior mid-range performance. The cartridge was designed for a large 2 lug bolt used in an AK, not a compact bolt used in an AR-15.

    5. 6.8mm projectiles have shown to have BETTER barrier performance than 6.5mm projectiles of similar construction (again, see Roberts 2008 report on barrier performance). While this does not matter much for hunting applications, so many forget the origins of the cartridge and it's purpose, it was intended to kill human beings, which are far more dangerous than deer or hogs...which may wear tactical vests with loaded AK or AR steel magazines, hide behind barriers such as walls or behind car doors, be inside a vehicle (auto glass)...These points are also left completely unaddressed in these often moronic arguments. What's your application? If it's paper target shooting and some hunting, 6.5 G is a better choice, but if it's self defense and or hunting, 6.8 SPC is a better choice.

    6. A non-expanding projectile (beyond fragmentation or expansion range) is still 100% lethal with proper shot placement (CNS hit or vital organ hit such as liver or heart) on human targets. Instant incapacitation is less important at longer ranges than at shorter ranges (CQB) due the ability to more easily hide behind barriers and accurate return fire (especially when wounded, even if not fatally or with delayed death), which is why the military considers it's cartridges to be combat effective at ranges well past fragmentation / expansion ranges often considered the limit for hunters. Often a balance of penetration and soft tissue damage is more desirable than just trajectory / KE. In that case there is STILL little meaningful difference between 6.5 G (1510 FPS @ 500y for 123gr AG) and 6.8 SPC (1517 FPS @ 500y for 110gr AG) at ranges a 14.5" barreled AR-15 is typically useful in combat (about 500 to 600 yards unless it's a special variant).

    7. Military units often use even shorter barrels in the 10 to 12" range, for which 6.8 SPC preserves muzzle velocity even better than 6.5 G. This is yet another critical point for military applications. Lets not forget the origins of the cartridge and why it was made the way it was. Jack of all trades, master at none. Despite the fact that the military ultimately abandoned 6.8 SPC, they are going forward with a 6.8mm replacement for the aging .308 / 7.62 NATO with one key player being the .277 SIG Fury hybrid cartridge pushing 80,000 PSI and nearly 3,000 FPS in 130gr from a 16" barrel. They are going to achieve 7.62 NATO performance in shorter barrels with trajectories closer to 6.5 Creedmoor.

    At this point, I would consider 6.8 SPC to be akin to a .270 Short. For reference, Hornady's ballistic data for 6.5 G is for 24" barrels originally, I shaved off exactly 200 FPS (25 fps per inch) to approximate a 16" barrel velocity. I also found some videos of a chronograph of a 16" barreled 6.5 G AR-15 at nearly the predicted velocity (I think they got 2415 fps on a warm day). While not perfect, it's close enough that in practical terms +/25 FPS isn't going to change information to a meaningful degree.

    My application has always been a high performance fighting gun, essentially a RECCE rifle. Do it all, but not the best at any one thing. 6.8 SPC cartridge fit that bill much better than 5.56 NATO (less lethality both direct and through barriers, much shorter frag ranges) or 6.5 G (bolt reliability, terminal performance against barriers lacking) in terms of overall performance out to 400~500 yards on hostile human targets. For those not familiar, this is the general concept of a RECCE rifle: https://www.pewpewtactical.com/best-recce-rifles/

    In fact, the hunters have proven the top performing 6.8 loads can even provide reasonable frag / expansion out to 400 yards, ranges 5.56 NATO could only dream of achieving enhanced lethality. It really is a great cartridge for the AR-15, but no, I never considered it a long range cartridge like 7.62 NATO or 6.5 Creedmoor both of which massively outperform 6.5 G and 6.8 SPC at longer ranges.
    Last edited by win&legend; 12-15-20 at 10:38.

  7. #97
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    Quote Originally Posted by win&legend View Post
    1. Longer but smaller diameter projectiles have LESS drag while flying through the AIR (ballistic performance) than larger diameter projectiles of similar weight but also LESS drag when traveling through the TARGET (terminal performance), what favors them in preserving KE / velocity while in flight works AGAINST them when trying to actually damage the target. This FACT seems to be lost entirely in just about every argument and I never see it mentioned when comparing 6.5 G to 6.8 SPC. Bigger diameter bullets tend to expand more consistently and to larger diameters than longer skinnier bullets.
    0.277" is only FIVE PERCENT greater than 0.264" — this FACT seem to be lost in just about every argument about the inherent advantage of one over the other.

  8. #98
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    Excellent post.
    RealeyesRealizeRealLies

    BCM 16" RECCE MK2 DkBrz, Custom Mk12 Mod1 built by Monty LeClair, 16" Middy w/ HCS RECCE barrel, A5, Young NM BCG, SSP, Geissele NM rail, Ops Inc., Super CH. 14.5" middy Noveske Afghan X3, 10.3" pistol DD barrell, Benelli M4, Ruger 10/22 w/Victor stock, GLOCK 17 Gen 4, Dan Wesson Valor Duty Coat, Dan Wesson Valor Blue, Dan Wesson Silverback 10mm, S&W 27 4"

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  9. #99
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    I've always thought the 6.8vs6.5 ballistic arguments were so stupid because either one of them max out at around 400yds anyway, as far as effectiveness goes, beyond that you're not gonna have a lot of energy left for expansion. But I just figured if the 6.5G fanboys wanted to jerk each other off about punching paper at longer ranges then they can just go right ahead. I'll keep shooting my 6.8.

  10. #100
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    Quote Originally Posted by kirkland View Post
    I've always thought the 6.8vs6.5 ballistic arguments were so stupid because either one of them max out at around 400yds anyway, as far as effectiveness goes, beyond that you're not gonna have a lot of energy left for expansion.
    If expansion range is your measure why not shoot 77 grain 5.56?

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