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300Blackout Vs 6.8

Discussion in 'Rifle Country' started by samuelcmm, Oct 9, 2012.

  1. samuelcmm

    samuelcmm Well-Known Member

    So I've searched around and I can't seem to find any direct comparative information on the two. So what are the BC coefficient both from 16'' barrel. What is the maximum efective range, Drop at 100,200......500 yards and which would YOU prefer if you were going to shoot 3 gun matches (eventually I will be able to get a suppressor however as Im starting full time college next semester I wont have the money) I guess ill have to convince my dad that he wants one :D. Thanks
  2. brian923

    brian923 Well-Known Member

    personaly would go with the 6.8 spc. I think its a better all around cartridge. it has bullets made specifically for the shorter round. these include hunting bullts made to expand at lower velocitys. was watching TACTV with Larry Vickers, and theh had the 300. blk on. it had roughly 14-16 inches of drop at 200 yards. its been awhile since I have looked over some 6.8 ballistics, but I think its less than that. the 300 just dosent have the case capacity with the .223 case. it would be a fun round inside 150 yards, but I think I would personally go 6.8. I had a 6.8 upper that would put 90 grainers in a 1/2 inch 5 shot group at 100. and 110 prohunters in 3/4 inches with only a 1" drop in poi witb the 90's. I really regret selling that upper.
  3. snakeman

    snakeman Well-Known Member

    the 6.8 is definitely a better, flatter shooting, harder hitting cartridge. However, blackout ammo is cheaper and you can use the bolt and mags from your 5.56 upper. I built a 6.8 and would do it over again if I had to choose between the two. I also like the 6x45 though and will build one of those in the near future.
  4. bikemutt

    bikemutt Well-Known Member

    I just put a real nice 300 blackout on layaway today so I can't say first hand. I have the blessing of my trusted 'smith who showed me some 100 yd targets that were outstanding. Ammo is plentiful here, if not cheap.
  5. helotaxi

    helotaxi Well-Known Member

    If I wanted to be competitive in 3-gun, I wouldn't shoot either. Too much recoil.
  6. cfullgraf

    cfullgraf Well-Known Member

    It depends on what you want the rifle to do.

    6.8 SPC has more long range potential while the 300 BLK will operate suppressed better.

    The barrel is the only difference between a 300 BLK and 223 Remington AR so repair parts are very available.

    300 BLK uses standard 223 Rem magazines. 300 BLK has a higher magazine capacity than the same size 6.8 SPC magazine.

    I like my 300 BLK. A great 100 yard rifle. I have shot mine with 110 grain to 208 grain bullets. Got some 245 grain bullets to try.

    I will admit that I have not tried a 6.8 SPC.
  7. Z-Michigan

    Z-Michigan Well-Known Member

    Yes, and also too much expense. Either one will cost you double or triple what you would pay to run a 5.56 gun, and a 5.56 has a flatter trajectory as well. Paper doesn't care what hits it, and steel usually doesn't unless there are issues with hearing the hit due to distance.

    This is it in a nutshell. Also 300BLK makes it much easier to send a heavier payload - 150-175gr supersonic is quite realistic with 300, while 120 is the heaviest common bullet for 6.8 (though SSA now has a 140gr load with an attractive BC).
  8. ParChaser

    ParChaser Well-Known Member

    OK, so I was thinking about going to a .300 Blackout in 9" for Hogs with the thought most of my shots would be under 200 Yards. I was watching Larry Vickers show last night, and it left me scratching my head and wondering if that is my next round. I have a LWRC 16" 6.8spc & a LWRC 16" SPR 5.56. I was leaning on the .300 BO till I watched TacTv last night where they did a 50, 100 & 200 yard test with the 5.56, .300BO & 7.62x39 on MGM Steel Sillouette 12x18"...
    Results- 5.56 50, 100 & 200 yds tight group center mass.
    Results-.300BO 50yds 4" low of Center, 100yds= 6" low, 200yds 14-16" low
    Results- AK 50yds 1" Center, 100yds= 2-3" of Center, 200yds 14-16" low

    Don't remember the Ammo used for each but this was a little disturbing since I was looking into the .300 BO for my next aquisition. Your thoughts????
  9. justice06rr

    justice06rr Well-Known Member

    Parchaser, thanks for showing that info. I have all 3 cartriges you mentioned: 5.56, 300BLK, and 7.62x39. Here's my take:

    Its not surprising that 300Blackout and 7.62x39 have similar ballistics, although the 300BLK shot lower given the smaller case capacity. When you said you were thinking of going 9" on the 300Blackout for hogs, were you talking about a SBR/Pistol setup?

    300Blackout is optimal for short ranges and with suppressor use. Depending on your range, under 150yards you should be ok but a 9-inch barrel would obviously be a bit different due to the shorter length. If you already have 5.56/223 and 6.8, the 300BLK is a good round to go with. Just understand its purpose and limitations. The 5.56 and 6.8 will be better for longer engagements, but for anything under 150yards the 300BLK should be a good round.

    So in short, if you wanted to use the 300BLK for hogs it would be better to stick with a 16" barrel so you get better performance out of it. Remember that 300Blackout is designed really both for suppressed/unsuppressed use out of the same AR15 parts save the barrel. Its also more suited for CQB type situations, so knowing that, make your decision.

    You already have 5.56 and 6.8 so those would probably be better for hunting at farther distances over 200yards.


    Samuelcmm, depending on what type of 3-gun you plan to do, either 6.8 or 300BLK should be ok although the 6.8 will have the advantage if you have long distance rifle stages over 200yards. Anything less than that and the 300BLK should work well.

    Do you already have a 5.56/223 AR? If not I would highly suggest the 300Blackout for the purposes of better interchangeability with AR15 parts. If you already have a 5.56/223 then obviously 6.8 might be better, but only slightly.

    I personally love my 300Blackout AR :D . But for all-around multi-purpose use, you can't beat the ol' 5.56/223
  10. Girodin

    Girodin Well-Known Member

    If the 300 BLK is like 7.62x39 you lose little velocity going to a 9" barrel.
  11. David E

    David E Well-Known Member

    Not seen the show yet, but it's on the DVR.

    But it seems to me that if the BO had a 2" high zero at 100, then the 200 target would have hits 6"- 8" low. As it is, it sounds like its sighted in at 10 yds.
  12. justice06rr

    justice06rr Well-Known Member

    I don't know the actual numbers in velocity difference, but I would think a barrel length difference of 7" would have a significant decrease in the velocity of the bullet (from 9" barrel to a 16"). That's almost losing half of the barrel...

    I could be wrong though. Do you have any figures to prove that the x39 cartridge will not lose that much velocity with a much shorter barrel? Remember that 300BLK is slightly different and less powerful than x39. I think the similarities are more with 16inch barrels. When you change barrel lengths and shorten the 300BLK barrel, the difference in velocity is amplified.
  13. cfullgraf

    cfullgraf Well-Known Member

    Shooting low at 50 or 100 yards is just a sighting issue. Look at the relative difference.

    My 300 BLK loads with 125 grain bullets run about 2100-2200 fps, 155 grain bullets run about 1700 fps, and 208 grain bullets run about 1100 fps.

    At 100 yards, the 208 grain loads hit 8 to 10 inches below the 125 grain loads at 100 yards. Quite the rainbow trajectory.

    The 125 grain loads shoot fairly flat out to 100 yards, within the 2 inch difference noted on the television show.

    300 BLK was designed to be ballistically similar to 7.62x39 in an AR platform. Also, 300 BLK was designed for suppressed capabilities.

    I got my 300 BLK for a home/farm defense rifle. It is great for that in my opinion.
  14. samuelcmm

    samuelcmm Well-Known Member

    I do have a 223. I was looking for something new to add to my collection and these cartridges stood out to me. One more that a freind mentioned to me last night that i had forgoten about is the 30 remington ar so are there any thoughts on it. I would be reloading Also i forgot to mention that at first
  15. 68wj

    68wj Well-Known Member

    I will start my response with this photo:

    That is 3/8" mild steel that a father and son shot at 100 yards in September. Both were shooting 115 gr HP ammo. The 3 complete holes are the only attempts made by the 6.8, while the rest are the 300 BO. Since I don't have an appetite for steel, this doesn't exactly mean anything about performance on game, but is a nice comparison.

    Directly responding to your questions, let me see where I can help:
    It depends, what bullet? The 6.8 has factory loads from 85-140gr, and the BO is 110-225.

    On what? Coyote, deer, paper, etc? If hunting game you need to run the numbers of your chosen load for energy on target (ft.lbs) and velocity (to make sure the bullet expands and transmits that energy). If hunting paper, it is more a matter of knowing your gun and aiming accordingly.

    For paper killing games, .223.

    You can suppress either cartridge too, but if you want to start running subs then the 300 BO makes more sense. This is something the 300 Whisper guys have been saying and working on for years, but it took a name change and SAAMI submission to get the larger industry to listen.

    There is pretty good availability of both right now with some broad industry and cottage manufacturers. I would image that even more will exist next year. Not sure about who is working on anything for the BO, but Tula and Federal are both saying they should have something on the shelf in 2013.

    In the end, especially if you are reaching into the paterfamilias pocket, get both. :evil:
  16. Walkalong

    Walkalong Moderator

    Bullet drop is worried about way too much. As long as you know the ballistics of your caliber, you are good to go.

    Recoil of the .300 BLK is a little better to me than .223. I guess it is subjective.

    I bought 500 bullets for 6.8 when they were on sale, because I thought I was going to build/buy one.

    Then the .300 BLK came along with all it's benefits of cheap cases, the ability to shoot the cheaper 147 Gr pulled bullets available, no change to any AR part except the chamber, uses the same mags, soft (to me) recoil, etc. So I built a .300 and am very happy with it. The 155 Gr A-Max shoots well in mine at around 1775 FPS, and the cheap 147 Gr pulled bullets are great for plinking running around 1850 FPS.

    Wanna trade for some 6.8 projectiles? :)
  17. brian923

    brian923 Well-Known Member

    the cool thing with the 300 is the wide range of bullet selection. i guess if you use the 110 vmax or similar, you would have a good 200 yard coyote/pig gun. I might get one of these soon, just to play around with. I have. 308win, and a 30/06, and plenty of 223 brass. so it just might be in the cards... does anyone have any ballistic info for the 110 vmax in the 300blk?
  18. Girodin

    Girodin Well-Known Member

    My experience is that going from a 16" gun to an 11" gun I went from around 2300 to around 2100. That is, one string of one load, over one chronograph from only two guns though. I've seen others report similarly that they loose 150-200 FPS. Two hundred feet per second for a gun that is mostly an inside of 200 yards (300 max) gun is not a big deal to me. I've seen at least one 7.5" gun that was shooting at around 1900 FPS where a 11" gun was doing 2000-2100.

    I have no idea about a blackout. With a 7.62x39 there is nothing I would shoot with a 16" gun that suddenly I would feel uncomfortable using a 9-10" barreled gun for.

    I think this is largely true, given that you also know your zero, etc. For me its more an issue of drift. The more something drifts the more my errors in reading wind throw things off. I'm not great at reading wind. For people who can read wind better than I can this may not be as much of a concern. The same is true to an extent for judging range. At times I can use a range finder but other times I may not be able to. With a 5.56 for example I can use a 300 yard zero and have a 5" zone from 25 yards to 300. I'm still on a torso at 400. It nice to be able to put the sights on target and not have to worry if its 350 yards and not the 250 yards I'm estimating.

    But yes, to the extent I know, or can accurately measure distance, and to the extent I know my loads, and my zero and adjustments, bullet drop is just math and can be accounted for.
  19. Walkalong

    Walkalong Moderator

    I have shot them at 2200+ FPS, and could probably get 2300 with a slower powder. That would be a little flatter shooting than the 147 to 155 Gr bullets. Data is sketchy for the .300 BLK. There is not a lot out there yet. PM me and I will share the load. Naturally you will need to start low, work up, and use at your own risk.
  20. snakeman

    snakeman Well-Known Member

    Here's how I would rate these cartridges in relation to hunting.

    1. 6.8 spc: flat shooting hard hitting
    2. 7.62x39: hard hitting
    3. 300 black out hard hitting not as flat shooting as those above
    4. 5.56 flat shooting, not enough horsepower for much other than small whitetails and small game

    also, don't forsake the 6.5 grendel, although it's not as popular as the others it is a true performer. It has range, power, and low recoil. If it was more available when I built my 6.8 I would have probably built a grendel

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