6mm ARC Barrel Length

Turbwhistle

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What dies are you guys using? I been running hornady match grade, but think i want to try something else as i'm not a fan of the seating die.
 
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357Max

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    What dies are you guys using? I been running hornady match grade, but think i want to try something else as i'm not a fan of the seating die.
    Wilson FL bushing die. Works perfect for sizing down 6.5G Lapua brass. The Hornady die's are closer to a small base die and will leave a ridge @ the bottom of Lapua brass.

    For seating I'm using the SAC seater with a reduction bushing insert I made for the Grendel case.
     

    Jason.N

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    Does anybody here shoot the Proof CF 20” barrel in a gas gun? If so, what kind of groups are you getting with it and with which ammo?

    Thanks!
    I have a 20" stainless steel proof. About 200 rounds in. 108 factory was about .5-.75 moa at 100yds. 105 factory was about .75-1 moa. These are all 5 shot groups. I have done better with handloads. Just ordered 500 105 barnes match burners to develop a load with. Still haven't got around to loading up the MBs yet.
     

    hacabrera071

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    I have a 20" stainless steel proof. About 200 rounds in. 108 factory was about .5-.75 moa at 100yds. 105 factory was about .75-1 moa. These are all 5 shot groups. I have done better with handloads. Just ordered 500 105 barnes match burners to develop a load with. Still haven't got around to loading up the MBs yet.
    That’s great info bud! Thanks a lot!
     
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    jbpmidas

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    I didn’t spec it any different from regular Proof. I think it’s a +1 gas system. Proof barrels include the gas tube, so I didn’t pay much attention to the length.
     

    The Pizza Guy

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    I didn’t spec it any different from regular Proof. I think it’s a +1 gas system. Proof barrels include the gas tube, so I didn’t pay much attention to the length.
    Ok cool. Thank you for the info. Does your gas block stick out past your handguard? Do you run 15 inch handguard?
     

    Conrad

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    Does anybody here shoot the Proof CF 20” barrel in a gas gun? If so, what kind of groups are you getting with it and with which ammo?

    Thanks!
    I have one. I’m satisfied so far. Shooting factory 103 ELDX at 2650 to 2700. 50-85 degree temp swing. Sub MOA, probably averages .6-.75.

    Have only taken it 700 yd so far but it does well there and hits the steel noticeably harder than my long throat 223 with 80’s.
     

    loclass

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    Where did you pick up a 22" Proof 6 ARC barrel? I ask because Proof doesn't list a 22" on their website.
    What gas port size is on your proof? Is your gas system +1 or +2? Thank you

    I didn’t spec it any different from regular Proof. I think it’s a +1 gas system. Proof barrels include the gas tube, so I didn’t pay much attention to the length.
     
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    Dave__th3__ss

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    In case you are interested in 18in barrel on a bolt gun
    Factory Hornady 103 ELDX - 2641 avg
    Factory Hornady 105 BTHP - 2644 avg
    Factory Honrady 108 ELDM - 2623 avg
    Varget 27.5 (think thats too hot for AR) 103 EDX is 2571 avg

    So with an 87gr vmax with varget. Temp today was approximately 28-32°
    Out of a 20” faxon 1-7.5 twist

    Start load was 28.1 gr varget -2777fps
    End load was 29.2 gr varget- 2822fps

    So I’d say 27.5 is not to hot for an ar.
     
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    CWik

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    Hi All – Recently started reloading for my 16" Bartlein gas gun (rifle-length) 6ARC. Looks like the load data from Hornady, specifically their big-for-caliber bullets, has changed recently. I've been shooting Berger 109 LRHT and Berger 108 Elite Hunters with Hodgdon Leverevolution recently. Wanted to confirm the following, since QuickLoad and Gordon's Reloading Tool show that my charges aren't safe (but appear to be recommended by both Hornady and others on this forum:

    • 29.7 grains of Lever behind a 109 Berger LRHT loaded at magazine length is safe
    • 29.1 grains of CFE223 behind a 109 Berger LRHT
      • Anyone have any experience with this bullet and these kinds of charges?
      • Using the below attached Hornady load data as a reference, although I know that a 108gr (ELD) or 110gr (A-Tip) Hornady bullet isn't identical to a Berger 109
    • Are the other 6ARC reloading specs (from Berger, Hodgdon's website) just being especially conservative in their load data?
      • I'm seeing much more conservative load data for 6ARC elsewhere (from Berger, Hodgdon, etc.)
      • I'm guessing Hornady would be the ones willing to push the performance of the 6ARC and the load data for it since it's their baby
    Any and all insight on this would be greatly appreciated. Thanks all!
     

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    CWik

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    Hi All – Recently started reloading for my 16" Bartlein gas gun (rifle-length) 6ARC. Looks like the load data from Hornady, specifically their big-for-caliber bullets, has changed recently. I've been shooting Berger 109 LRHT and Berger 108 Elite Hunters with Hodgdon Leverevolution recently. Wanted to confirm the following, since QuickLoad and Gordon's Reloading Tool show that my charges aren't safe (but appear to be recommended by both Hornady and others on this forum:

    • 29.7 grains of Lever behind a 109 Berger LRHT loaded at magazine length is safe
    • 29.1 grains of CFE223 behind a 109 Berger LRHT
      • Anyone have any experience with this bullet and these kinds of charges?
      • Using the below attached Hornady load data as a reference, although I know that a 108gr (ELD) or 110gr (A-Tip) Hornady bullet isn't identical to a Berger 109
    • Are the other 6ARC reloading specs (from Berger, Hodgdon's website) just being especially conservative in their load data?
      • I'm seeing much more conservative load data for 6ARC elsewhere (from Berger, Hodgdon, etc.)
      • I'm guessing Hornady would be the ones willing to push the performance of the 6ARC and the load data for it since it's their baby
    Any and all insight on this would be greatly appreciated. Thanks all!
    Please feel free to point my questions to another thread if there's one which is more applicable. Thanks
     
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    357Max

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    Hi All – Recently started reloading for my 16" Bartlein gas gun (rifle-length) 6ARC. Looks like the load data from Hornady, specifically their big-for-caliber bullets, has changed recently. I've been shooting Berger 109 LRHT and Berger 108 Elite Hunters with Hodgdon Leverevolution recently. Wanted to confirm the following, since QuickLoad and Gordon's Reloading Tool show that my charges aren't safe (but appear to be recommended by both Hornady and others on this forum:

    • 29.7 grains of Lever behind a 109 Berger LRHT loaded at magazine length is safe
    • 29.1 grains of CFE223 behind a 109 Berger LRHT
      • Anyone have any experience with this bullet and these kinds of charges?
      • Using the below attached Hornady load data as a reference, although I know that a 108gr (ELD) or 110gr (A-Tip) Hornady bullet isn't identical to a Berger 109
    • Are the other 6ARC reloading specs (from Berger, Hodgdon's website) just being especially conservative in their load data?
      • I'm seeing much more conservative load data for 6ARC elsewhere (from Berger, Hodgdon, etc.)
      • I'm guessing Hornady would be the ones willing to push the performance of the 6ARC and the load data for it since it's their baby
    Any and all insight on this would be greatly appreciated. Thanks all!
    Gordan's Model for Lever has been out to lunch in my experience for both 6ARC & 224Valk. With all variables input correctly including gas system, it's been 120fps off or more.

    29.7 gr Lever works well in my gun with 109's @ mag length.
    Lever produces a lot of gas so adj gas block would be helpful especially for top end loads if you don't want to beat the hell out of brass and bolt lugs.

    Search the big 6ARC thread for a lot of load specifics. I've posted a lot of loads in that thread.
     
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    Bluedog82

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    What’s the real-world difference between a 16 and 18” bbl? I’m building an SPR style rifle and already have a 16” 556. I know it’s “optimized” for 18” but if the real velocity difference isn’t very significant I don’t see the point in making a gun longer than it needs to be (mine will be suppressed 100% of the time).
     
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    TonyTheTiger

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    What’s the real-world difference between a 16 and 18” bbl?
    Zero. The velocity difference can be up to 100fps on the high side to negative velocity gained if you happen to get a fast 16" and a slow 18". I've seen plenty of chrono data to back that up, and seen plenty of longer range use to come to the conclusion that 50fps (a pretty safe rule of thumb velocity gained from 2") means very little.
    The main thing is that common lore says 18" can run a rifle gas system and 16" can not. Common lore is wrong, but it exists. Rifle gas is so much nicer than mid that if I cared about fudd-lore I'd be in the 18" barrel camp.

    Edit: just realized I was in the 6ARC thread and replying with a 5.56 mindset. Doesn't change what I wrote above that much.
     
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    CWik

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    Gordan's Model for Lever has been out to lunch in my experience for both 6ARC & 224Valk. With all variables input correctly including gas system, it's been 120fps off or more.

    29.7 gr Lever works well in my gun with 109's @ mag length.
    Lever produces a lot of gas so adj gas block would be helpful especially for top end loads if you don't want to beat the hell out of brass and bolt lugs.

    Search the big 6ARC thread for a lot of load specifics. I've posted a lot of loads in that thread.
    @357Max – Thanks for confirming the load data and what I'm seeing on my LabRadar as well. Seems like us bandleaders are a bit ahead of the published load data for the 6ARC. Understandable, since it's newish and they likely want to keep the pressure/data conservative to start with. Will try out the 29.7gr Lever behind the Berger 109's. Much appreciated!
     
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    CWik

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    Zero. The velocity difference can be up to 100fps on the high side to negative velocity gained if you happen to get a fast 16" and a slow 18". I've seen plenty of chrono data to back that up, and seen plenty of longer range use to come to the conclusion that 50fps (a pretty safe rule of thumb velocity gained from 2") means very little.
    The main thing is that common lore says 18" can run a rifle gas system and 16" can not. Common lore is wrong, but it exists. Rifle gas is so much nicer than mid that if I cared about fudd-lore I'd be in the 18" barrel camp.

    Edit: just realized I was in the 6ARC thread and replying with a 5.56 mindset. Doesn't change what I wrote above that much.
    @Bluedog82 & @TonyTheTiger – Couldn't agree more. I have a 16" with rifle-length gas and it's such a smooth shooter and very reliable cycler. A bit of adjusting when tossing the can on it was all it needed and I haven't had a since malfunction. @Bluedog82 – as far as performance goes, I'm not seeing a heavier bullet (103 grains or more) begin to go transonic (1,341 fps as a proxy) until it's past the 100yd mark (according to Applied Ballistics calculator and my own LabRadar measurements) even using factory Hornady 103 grain ELD-X. Yes, I could have gone with an 18" barrel to get a bit more speed out of the rounds, but you're not truly getting a material improvement in MV until you're adding 4+ inches to the barrel (from 16"). The one caveat is that I opted for a 1:7" twist as opposed to the more standard 1:7.5" twist. Definitely helps keep the heavier bullets more stable – would recommend a 1:7" twist if you plan on shooting the heavier bullets, regardless of the barrel length you settle on. Glad to see more shorty 6ARCs being built!
     

    Dogtown

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    The 26" barrel showed up this morning so I'll be able to get you guys some long barrel data as soon as the flooding stops.
     

    Dogtown

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    I finally got to the range to do some pressure testing with different bullets and powders, so here's some numbers for you with a 26" gas gun barrel:

    All loads were using resized Lapua 6.5 Grendel brass, GM205MAR primers, and loaded to 2.26" COAL

    No pressure signs in any of these loads, so clearly they can be pushed a bit harder.

    110 A-Tip
    RL17 26.6-29.0
    2287-2501fps

    110 A-Tip
    Varget 24-26.2
    2330-2557fps

    95 VLD TGT
    ARComp 24-26.4
    2542-2782fps

    95 VLD TGT
    N140
    2382-2605