Gas length for 16" 6.5 Creedmoor

AK4900PA

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What gas system length would you guys suggest for a 16" 6.5 Creedmoor? I will be using an superlative gas block and while I want it to function unsurpressed it will be shot with the suppressor 99% of the time. Ballistic Advantage has a 16" with a mid length system while Wilson Combat uses an intermediate system. Anyone try a rifle length system on a barrel that short?
 

bigjake83

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    What gas system length would you guys suggest for a 16" 6.5 Creedmoor? I will be using an superlative gas block and while I want it to function unsurpressed it will be shot with the suppressor 99% of the time. Ballistic Advantage has a 16" with a mid length system while Wilson Combat uses an intermediate system. Anyone try a rifle length system on a barrel that short?

    Why would you even bother with a 16" 6.5CM??
    that's completely counterproductive you might as well do a .308
     
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    AK4900PA

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    I'm not trying to be rude but making a 16" 6.5CM is just pointless, if you want something in a 6.5 to run suppressed that is effective build a 6.5 Grendel.

    .308 is proven effective in short barrels, the CM....not at all.

    I already have a 12.5" Grendel and a 16.5" .308. The 16" Creedmoor fills a niche for me. Ballistics are equal to, or better, than a 24" .308 without the extra weight and length. For a gun that will likely never shoot at a target beyond 600 yards it's plenty.

    I've looked for off the shelf options, but I think I'll likely spend the extra coin and have Craddock spin up a Bartlein for this build.
     

    Niles Coyote

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    .308 is proven effective in short barrels, the CM....not at all.

    Show me a 308 AR that can run a Berger 215 hybrid at 2400-2500 with a 16" barrel. I know 28-30" 308's in a bolt rifle can get them going in the 2650-2700 using purpose built chambers and small primer brass and a lot of pressure... but I'd bet you'd still need a Win Mag to achieve the same a Creedmoor could do with a 130-150 grain high BC bullet in an AR.
     

    bigjake83

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    Show me a 308 AR that can run a Berger 215 hybrid at 2400-2500 with a 16" barrel. I know 28-30" 308's in a bolt rifle can get them going in the 2650-2700 using purpose built chambers and small primer brass and a lot of pressure... but I'd bet you'd still need a Win Mag to achieve the same a Creedmoor could do with a 130-150 grain high BC bullet in an AR.

    He's talking about using a 16" 6.5 CM!!

    The .308 at shorter barrel length handles the pressure a lot differently.
     
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    bigjake83

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    1-not high, just able to use a ballistics calculator.

    2-considering you've added nothing of any value to this thread I would very much appreciate you focusing your efforts elsewhere.

    Please show us all of your ballistic findings of how a 16" AR chambered in 6.5 creedmoor can out performer 24" .308

    Don't worry... I'll wait
     
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    AK4900PA

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    5 posts and you've added absolutely nothing of value to the original question regarding gas system length. I didn't ask for your approval or opinion on barrel length. Move the fuck on, go have a drink and enjoy the new year.

     

    AK4900PA

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    So anyways...back to the original topic. Any reason to go with the mid or intermediate length over rifle length in a primarily suppressed application?
     

    FCS

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    Rifle gas would be best option, intermediate at minimum. What suppressor?
     

    FCS

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    Still going to have a fair bit of back pressure with SAS Reaper. If you have Craddock Precision do the barrel, I'd go rifle at minimum and +1" gas wouldn't hurt you any. Craddock can make you a +1" gas tube.
    You'll have quite a bit higher port pressure, more gas volume with the 16.5", 6.5 Creedmoor then you do with 16" bbl'ed 308.
     

    bigjake83

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    5 posts and you've added absolutely nothing of value to the original question regarding gas system length. I didn't ask for your approval or opinion on barrel length. Move the fuck on, go have a drink and enjoy the new year.

    Then stop posting your Bullshit Facts about how a 16" 6.5CM can out perform a 24" .308.

    It can't!! The longest Gas System you can run on a 16" CM is an intermediate.. the pressure alone would destroy your brass after the first firing along with any potential accuracy that is why the .308 is the only one that can perform well in 16" barrel due to its pressure curve.

    Just face the fact that you don't have a Fucking clue about what you're talking about in regards to ARs.. oh and we are all still waiting for your "Ballistic Findings" on how a 16" 6.5CM (which there's no real data for in ARs) and how it is ballistically superior to a 24" .308
     
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    bigjake83

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    Still going to have a fair bit of back pressure with SAS Reaper. If you have Craddock Precision do the barrel, I'd go rifle at minimum and +1" gas wouldn't hurt you any. Craddock can make you a +1" gas tube.
    You'll have quite a bit higher port pressure, more gas volume with the 16.5", 6.5 Creedmoor then you do with 16" bbl'ed 308.

    Thats the problem, and you can confirm this with Craddock, ...Gas Port erosion!! that's why the intermediate is the longest you can do on a 16" SS barrel, if you move to a 18" barrel it will work. And you have to use a specific type of steel, Krieger and Bartlein will not work.. Frank at CLE is have this same issue.
     

    AK4900PA

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    Then stop posting your Bullshit Facts about how a 16" 6.5CM can out perform a 24" .308.

    It can't!! The longest Gas System you can run on a 16" CM is an intermediate.. the pressure alone would destroy your brass after the first firing along with any potential accuracy that is why the .308 is the only one that can perform well in 16" barrel due to its pressure curve.

    Just face the fact that you don't have a Fucking clue about what you're talking about in regards to ARs.. oh and we are all still waiting for your "Ballistic Findings" on how a 16" 6.5CM (which there's no real data for in ARs) and how it is ballistically superior to a 24" .308

    "We" are not waiting for anything. You are. You are the only internet badass around right now.

    You are correct in regards to the numbers specific to semi autos. I'm going off numbers for a bolt action, but as far as drop and drift the longer barreled .308 vs the shorter 6.5 are very close. Obviously energy on target is better with the .308 at shorter distances, but not enough to concern me for deer sized game. I run factory ammo, having had good luck with Hornady in other guns that is what I used as a comparison. 143gr ELD-X @ ~2500fps out of a 16" barrel is ballisticaly neck and neck with a 178gr ELD-X @ 2600fps out of a 24" barrel.

    Why you care so much how a complete stranger spends their money is beyond me, but I've grown tired of this. I've asked you as politely as possible to move on and you've been unable to do that so I'm going to stop responding and just let this thread die. I'll call Craddock later this week and see what they suggest.
     
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    FCS

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    Intermediate is going to give you way too much dwell time, going to tear up brass with a 6.5 Creed with normal burn rate powders used with 6.5 Creed.
    Rifle or +1" gas system may well have more port erosion but isn't going to be any harder on the brass then trying to extract case while chamber pressure is higher.
    Definitely a pick your poison situation, I'd live with the port erosion and keep adjusting the gas block to compensate for port getting larger. Increased dwell time from an intermediate gas system, just no good way to countering that IMHO.
    18" would be as short as I'd go personally and a 20" barrel with right contour isn't going to weight enough more than a 16.5" barrel for me to worry about. I see appeal to the 16.5" barreled 6.5 Creed AR but I do think performance of a 6.5 Creed in an AR below 20", even more so below 18", is going to take a much bigger hit then one would see in a bolt rifle. AR has more dynamics that come into play, 16-18" barreled bolt rifle in 6.5 Creed has far fewer variables and will most probably not lose quite as much performance.

    16.5" barreled 6.5 Creedmoor in an AR you'll be about 2650 fps with a 130 AR hybrid. 600 yards that is 93" of drop, 26" of drift and 926 ft lbs of energy.
    24" barreled 308 in an AR you'll be about 2550 fps with a 185 Juggernaut. 600 yards that is 102" of drop, 28" of drift and 1201 ft lbs of energy.
    16.5" barreled AR in 6.5 Creed does beat out a 24" barreled 308 in drop (9" less with 6.5 Creed) and drift (2" less with 6.5 Creed) but not energy (275 more ft lbs with 308) delivered on target.
    Shorter barreled AR in 6.5 Creed is not a shorter barreled bolt rifle in 6.5 Creed. ARs are not bolt rifles, you will not get the same velocity from an AR as you can get from a bolt rifle.

    We need experimenters, if AK4900PA wants a 16.5" barreled 6.5 Creed with a rifle or +1" gas system I don't see it being a "bad" thing. Okay, has faster gas port erosion....so what? Adjust gas down with gas block or heavy up buffer some more or put on a new barrel. Barrels are cheap, life is short and if AK4900PA has the $, time and desire to do a 16.5" barreled 6.5 Creedmoor with a rifle or +1" gas system then he should give it a whirl.
     

    bigjake83

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    16.5" barreled 6.5 Creedmoor in an AR you'll be about 2650 fps with a 130 AR hybrid. 600 yards that is 93" of drop, 26" of drift and 926 ft lbs of energy.
    24" barreled 308 in an AR you'll be about 2550 fps with a 185 Juggernaut. 600 yards that is 102" of drop, 28" of drift and 1201 ft lbs of energy.
    16.5" barreled AR in 6.5 Creed does beat out a 24" barreled 308 in drop (9" less with 6.5 Creed) and drift (2" less with 6.5 Creed) but not energy (275 more ft lbs with 308) delivered on target.

    Shorter barreled AR in 6.5 Creed is not a shorter barreled bolt rifle in 6.5 Creed. ARs are not bolt rifles, you will not get the same velocity from an AR as you can get from a bolt rifle.

    Well put...

    Where are you getting your MV INFO from on the 16.5 6.5CM??

    The 18" 6.5 CM from LaRue aren't even at 2650?

     

    FCS

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    I've gotten 2800 fps from an 18" barreled 260 AR, I'm pretty confident I could get 2650 from a 16.5" barreled 6.5 Creedmoor AR. I haven't done a 16.5" Creedmoor AR but I'm hard pressed to believe one would lose 150 fps by going 1.5" shorter.
    Yeah, there were some special gyrations but nothing too crazy.
     
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    bigjake83

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    I've gotten 2800 fps from an 18" barreled 260 AR, I'm pretty confident I could get 2650 from a 16.5" barreled 6.5 Creedmoor AR. I haven't done a 16.5" Creedmoor AR but I'm hard pressed to believe one would lose 150 fps by going 1.5" shorter.
    Yeah, there were some special gyrations but nothing too crazy.

    Is that with the 123's??

    Every person I know who shoots with a 22". 260/6.5CM using 143/139s aren't even close to that, I'd like to see your load data.

     

    bobke

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    Different issue I know, but in dealing with Craddock, be certain to discuss the feed cone, and any concerns you might have regarding proper feed of HPBT style bullets such as Scenars and the like. This had been noted by myself and several others in another thread. I could get AMax to feed, but nothing else. Dialed up proper, wider bevel and went to JP extension-from a BAT, and issue gone. Can’t say which was causal factor because both issues fixed at same time, but required fix, elsewhere.
     

    GBMaryland

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    I pickep up a Larue 22 inch 6.5CM upper with a “+2” gas system. So far the brass isnt having any signs of over pressure... (I’ve cleaned it all and given it the once over...)

    In addition to the longer gas system, I also notice the firing pin / hole in the bolt seems to be smaller than the one on my spare bolt for the original 7.62 OBR system.

    When I spoke with a buddy of mine (manufacturer) he mentioned that using bolt gun full powered loads tends to blow out gas tubes. My assumption was that is with an unmodified gas system back when AR 6.5CM bulilds were somewhat new.
     
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    GBMaryland

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    Is that with the 123's??

    Every person I know who shoots with a 22". 260/6.5CM using 143/139s aren't even close to that [2800], I'd like to see your load data.

    Factory ammo with my rifle is showing ~2725-2775FPS with 140s... those are in the general vicinity of 2800 BUT with a 22inch barrel AND a supressor.

    Sellier & Bellot 65 Creedmoor 140gr FMJ BT Suppressed, Remington 140gr PSCL Benchmark 65 Creedmoor Suppressed

    Without the supperor I’m seeing about 50FPS less, and I’m using a .338 YHM can. I suspect there may be more backpressure with one of the 30 cal cans.

    My understanding is the factory ammo is using a propreitary powder blend. Not to mention those rounds above are not ELD, just normal bullets. The S&B brass is very consistsant.

    I just picked up a large quantity of 4350 and I’m going to start seeing what developes with 140 Hornady HPBTs (non-ELD)
     
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    Cavitation

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    Just in case it matters. My 20 inch AR 6.5 C with hot 123 amax loads only gets a tad over 2700 fps.
    I would love to see your findings on a 16 inch. I have been thinking of swapping out for a 24 inch to get me closer to 2800.
     

    Birddog6424

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    DMONEY

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    THE ALL-NEW BARRETT REC 10 HAS RECEIVED A SUBSTANTIAL MILITARY CONTRACT.
    ”We've been working on the REC10 behind-the-scenes for more than two years. Before we bring a rifle to market, we have to know it meets the standards of the most demanding users in the world – the armed forces. Winning this contract further confirms, we’ve done our job.” - Chris Barrett, President.

    The Barrett family, distributors, and customers have a long standing respect for the armed forces and understand the need to equip them with the best. Development and manufacturing resources are dedicated to fulfilling the contract order immediately.

    Once fulfilled, the REC10 will be available through distributor and retail partners. Barrett will continue to provide updates. Please contact [email protected] with any questions.




     

    Birddog6424

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    ^^ But that's the .308, as he clearly states at the 16 second mark. I think we all know the 308 will run pretty good with shorter barrels. No where in that video does he say anything about the 6.5 Creedmoor.
     

    DMONEY

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    WOW...... you wont be Happy till i ship you one to your door ... and then it would be the WRONG color ,,,, lol :)

    While Barrett Firearms Manufacturing is best known for their .50 BMG anti-materiel rifles they also produce a series of AR-based designs, the REC7, offering both piston and direct gas impingement systems. While the REC7 is chambered in 5.56×45 or 6.8 SPC, Barrett has unveiled the new REC10 which chambers larger rounds including 7.62x51mm, .260 Remington, and 6.5 Creedmoor.

    and here is the link .... yes barrett will be offering a 16" 6.5 creedmoor / and as stated above POF already does ....

    http://www.thefirearmblog.com/blog/2017/12/28/barrett-firearms-introduce-rec10/
     
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    Birddog6424

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    You're missing the point.

    Its NOT on the market yet. We know nothing about it other than the marketing plug. We don't know how it runs. We don't know what kind of velocities it will get, we don't know the gas tube length, we don't know if it destroys your brass. We don't know if it runs very finicky. We don't know if it's super hard to tune. We could write a book with what we don't know..

    We don't even know if it will actually make it to market at this point. All we have seen is a 308.

    To claim Barret has it worked out on a rifle no one has seen is premature. It may be a complete turd and Barret is reluctant to release it. Who knows at this point.
     

    Cavitation

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    I dont understand why it seems so impossible to produce a 16 inch 6.5 Creedmoor? Adjustable gas blocks and playing with tube lengths and buffer weights, seem to make almost everything run. (halfway decent) I dont think It is going to be any harder really that anything else
     

    Bigshooter42

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    I’ve got a 16” Faxon barrel with mid-length gas on a recent build. I’m still tweaking loads but have managed to get 2700+ with 120 ELDs, ~39 gr of Varget and small primer brass. Had to change to a JP HP bolt and heavy buffer spring/weight to get it to run smoothly, but no issues now.
     
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    SLG

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    I have a 14" 6.5 creedmoor in an Aero build. Ballistic advantage barrel. Comes as a truck axle, but Spartan Precision was able to turn it down nicely and make it much handier. Carbine length gas, seems to run just fine. I have not chrono'd it yet, but truthfully, I don't really care what the numbers are. It does what I want it to do.

    And for the record, I do not recommend a 14" 6.5. Mine was built for a very specific purpose, and it fits the bill well.
     

    Birddog6424

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    OK here ya go 16" 6.5 creedmoor ..on the market and available ....

    Well there it is. I like that you went out there and found that ;0

    Looks like it ran ok. Bit of a dork to run his scope mount backwards, for any reason. He had to extend the stock all the way out to get eye relief.

    I've shot that rifle in another caliber. They had some play guns at a PRS Gas Gun Series match last year with DMR II's on them. Not a bad AR for Savage.
     
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    JFComfort

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    Old thread I know. I did a 16.5” with a +1” gas system and am liking it so far. I will be doing another barrel and incorporating more refinements. I also did a rifle gas length barrel for comparison.

    132FC446-3860-4CB3-A5AF-0A43E49E3F35.jpeg


    7162EB95-F277-40DF-B3CE-467938E897C9.jpeg
     
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    Luke G

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    Old thread I know. I did a 16.5” with a +1” gas system and am liking it so far. I will be doing another barrel and incorporating more refinements. I also did a rifle gas length barrel for comparison.

    View attachment 7300079

    View attachment 7300078
    Whose barrels are you using if you don’t mind me asking? Looking for a rifle length 16 but having trouble finding many options. Looks like that one shoots well if that group is anywhere near what it averages.
     

    JFComfort

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    Whose barrels are you using if you don’t mind me asking? Looking for a rifle length 16 but having trouble finding many options. Looks like that one shoots well if that group is anywhere near what it averages.

    I’m still shooting a variety of factory ammo to see what it likes. Hornady 147 and Winchester 140 have showed exceptional results. Hornady 140 did 0.8 MOA averaging four 5 round 100 yard groups. I want to shoot Federal 130 and a few others before doubling back.

    Both barrels are Bartlein 5R’s that I chambered, ported, etc. I haven’t finalized my gas port diameter yet and am currently using an adjustable gas block. My “finalized” barrel will not utilize an adjustable gas block.
     
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