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Thread: Why not 1/8 twist?

  1. #21
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    Quote Originally Posted by TRIDENT82 View Post
    Firstly, I've received two new barrels the last several weeks to evaluate, and both are 1/8. Thus far both have shown to be accurate barrels using a number of different weighted projectiles. That said, I believe currently it's en vogue to do barrels in 1/8...and has been over the last cpl. years at least. On paper it's makes perfect sense....a twist rate that accommodates not only heavy projectiles like 1/7, but also should have the ability to accurately shoot light projectiles that in theory go best with a 1/9.

    The rub is the fact that my real world observations, and testing haven't shown the 1/8 to shoot lighter projectiles more accurately, and moreover they have shown to be less accurate with heavies than the 1/7. Every 1/7 I can remember testing has shot 40-60gr. poly tipped loads as good as it shoots 77gr. SMKs. I'm still waiting on my first lightweight projectile to vaporize coming out of a 1/7 barrel. So quite honestly, there is no real good reason for a 1/8 other than the great sounding theory that it shoots lighter bullets better than the 1/7. My pair of Rock 5R SS 1/7 barrels shoot the Hornady 40gr. Vmax into roughly a MOA 10rd group.
    can you tell us which 1/8 barrels you're testing and which projos?

    also, can I ask if you measured twist in those barrels? as you know, a lot of barrels are marked as 1:7 or 1:8 but actually measure something different. (ie., it's common to find 1:8 marked barrels actually measure 1:7.7, etc...)
    Last edited by ra2bach; 02-15-14 at 14:45.
    never push a wrench...

  2. #22
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    What are you selling? His rifle is fine the way it is. The way AR's are being employed today outside of Magpul Mags, H-buffers, and Extractor upgrades for carbines (Something that was known back in the 70's btw) is all fluff. You don't need all that crap to have an effective, well functioning firearm. 1/9 is fine and dandy. (Where do you think most of the guys today learned what they know?) Anyway, there it is. Your rifle is good the way it is original poster. Barby Doll for men stuff is no substitute for knowing your weapon. Most of these guys shoot competition. If the fear hit them they would freeze up and all the gear in the world wouldn't save 'em. Even the vets today hardly ever engage at close range with an enemy. Ask they guys who have. They'll agree.

  3. #23
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    None of us are trying to sell anything. We are just trying to prevent the spread of misinformation so when people who are trying to learn come across these threads, they don't absorb the bad stuff and get the right answers. You are spreading the bad stuff, and make a lot of unproven or easily-falsifiable claims. Please read more.

  4. #24
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    Quote Originally Posted by MidwayHazard59er View Post
    What are you selling? His rifle is fine the way it is. The way AR's are being employed today outside of Magpul Mags, H-buffers, and Extractor upgrades for carbines (Something that was known back in the 70's btw) is all fluff. You don't need all that crap to have an effective, well functioning firearm. 1/9 is fine and dandy. (Where do you think most of the guys today learned what they know?) Anyway, there it is. Your rifle is good the way it is original poster. Barby Doll for men stuff is no substitute for knowing your weapon. Most of these guys shoot competition. If the fear hit them they would freeze up and all the gear in the world wouldn't save 'em. Even the vets today hardly ever engage at close range with an enemy. Ask they guys who have. They'll agree.
    RPM stabilizes the bullet in flight, not barrel length. A 1:9 twist is good for shorter, blunter bullets and while going to a longer barrel results in higher velocities, the gain in velocity may not be enough to increase the RPM to a level needed to stabilize longer, pointier bullets.

    Sierra used a doppler radar to show that their 69 gr Matchking bullet was indeed more stable when launched from a barrel with a 1:7 twist vs a 1:8 or 1:9.

    kest_01 wants a versatile twist to use with bullets from 55-77 grains. Unless he gets really lucky, he's not going to get that versatility with 1:9 twist.
    Last edited by MistWolf; 02-15-14 at 17:40.
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    5. HA-HA!!

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  5. #25
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    MidwayHazard59er... Please check your PMs before posting further in this thread.
    2012 National Zumba Endurance Champion
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  6. #26
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    OP, I don't see any stigma with 1/8 twist bbls. I have a rifle with a Lilja bbl in 1/8 and I'm quite happy with it. I can use 55gr for training courses and use 70, 69, and 77gr for defensive/distance shooting. My next build will likely be a 1/8 also. Do your own research but it works quite well.

    Quote Originally Posted by MidwayHazard59er View Post
    11th ACR LRRP, 3rd Squadron, 4th Troop, '68-'69. I dare say I know a little more about pragmatic usage of the AR than you do son. Don't be rude.
    Thank you for your service. Now please understand that having used a weapon system (35 years ago) does not qualify a person as an expert on the technical aspects of it. Your rifle in VN had either a 1/14 or 1/12 twist. The switch to 1/9 was for the SS109 projectile (62gr).

    A person could have been the most badass tier 1 commando ever. That doesn't mean he is qualified to teach shooting or to advise on things like twist rate, bbl steel, etc. Military service itself is not going to get a person a pass when posting misinformation on this site.
    Before you suggest that licensing, background checks, or other restrictions for the 2nd Amendment are reasonable... Apply those same ideas to the 1st and 4th Amendments. Then tell me how reasonable they are.

  7. #27
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    It is amazing to me how much misinformation is out there. I like this forum because members are not afraid to call BS and the record gets corrected. Also the technical threads are fantastic, but sometimes take hours to read. Good stuff, thank you all.
    Last edited by ScottsBad; 02-15-14 at 15:27.

  8. #28
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    Quote Originally Posted by ScottsBad View Post
    It is amazing to me how much misinformation is out there. I like this forum because members are not afraid to call BS and the record gets corrected. Also the technical threads are fantastic, but sometimes take hours to read. Good stuff, thank you all.
    X2
    Thanks for the good info on twist rates

  9. #29
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    I had thought about switching my 1 in 7 barrels to 1 in 8 twist because most of my ammo is 55 gr fmj factory or reloads. I was worried that they would do terrible from the reading I'd done on the interwebs. Instead I did what most on this board recommend: shoot it and find out. I even had some 40 gr varmint bullets I had reloaded and was worried about them coming out like birdshot, they didn't. I use them for practice ammo because they shoot about the same as my xm193 or 855. My 55 gr reloads usually shoot 1 to 1.25 moa when I do my part. The factory loaded xm193 is usually 2.5 to 3 inches, about the same as the xm855.

    Would a 1 in 8 improve my groups? Who knows, every barrel is different it seems to me. I don't feel the need to try one out when I finally use up my current barrels either, 1 in 7 has been more than sufficient for my needs. A 1 in 9 might be more appropriate for 55gr loads I usually shoot but I sometimes use 69 and 77gr Nosler custom comps and they shoot very well in both my 1 in 7 barrels. Do you have a reason to go for a 1 in 8 twist? I think that's a better question than why not.
    Appeasement is never the answer in the face of naked aggression.

  10. #30
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    Rarely does somebody miss their target because their AR15 isn't accurate enough.

    Only time a quality rack grade AR isn't accurate enough is competition or perhaps varmint hunting.


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