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Thread: 16” 6.5 Creedmoor barrel worth it?

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    16” 6.5 Creedmoor barrel worth it?

    I’m toying around with the idea of a battle rifle or CSASS built around a 16” barrel chambered in 6.5 CM. I’ve built three AR10s in the past, all with 18” - 20” barrels, and I’d like to have something a bit more compact. I’d also like to try 6.5 CM as it seems to be all the rage these days. Realistically speaking, how does 6.5 CM compare to .308 when fired from a 16” barrel? I’m particularly interested in impact energy generated.

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    https://rifleshooter.com/2016/02/6-5...p-a-creedmoor/

    https://rifleshooter.com/2014/12/308...ty-28-to-16-5/

    The real problem with a creedmoor in a gas gun is pressure. A 16 in gun will need a long gas system and likely an adjustable gas block. Pressures being higher in sammi spec creedmoor ammo means higher port pressures.

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    I noticed a difference when I went from a 18" rifle gas to a 16" intermediate gas. The recoil got harsher as the other poster noted that 6.5 is a very high pressure and gassy round. My velocity took a hit as well. Lost about 75 FPS cutting off 2" of barrel on my 140gr IMR4350 handloads. Despite the objective draw backs I still really like my 16" creed moor. It's very short and compact for how far it shoots. Even at 16" I can still move a 140gr HPBT at 2550 FPS; which is ballistically similar to a 175gr at 2500 FPS which is what a lot of 24" 308 bolt guns make. I think it was only 10.5 Mils to 1k if I remember correctly.

    I am looking into trying some of the lighter for caliber loads in 6.5 CM. Right now the 95gr V-max and 108gr Lapua look like a good choice.
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    My gut reaction is Hell No. Even at 18" I'm a little meh. But I'm still stumped at what I'd do instead for a "compact" hammer. We have a buddy who shoots 155 TMKs out of like a 13.5 .308 gasser and loves it. I would never do a 308 that short. But he's really happy.
    "What would a $2,000 Geissele Super Duty do that a $500 PSA door buster on Black Friday couldn't do?" - Stopsign32v

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    If you want to try out the 6.5 to see it’s advantages I’d start with a full size barrel.

    But if you have a specific need for around full sized .308 ballistics with a shorter barrel the 6.5 will do.

    For 6.5 or .308 I would consider a “handier” weight build before a short barrel. A lightweight handguard, no longer than it really needs to be, with a medium or moderately lightweight 20” barrel is nice. Much less and I would start looking at AR-15 sized options.


    The 95gr V-max has been really good in my .260, very accurate and even lighter recoil.

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    Hammer_Man-What receiver set are you going to use? I'd love to see how your build turns out. I've thought of doing a large frame build a couple times but I'm clueless with the large frame builds.

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    Thanks for all the replies, I recently lost my job so I’ll have to put my plans on hold for now. In regards to usage, I want to build a battle rifle with a barrel no longer than 16” to keep the center of gravity closer to the middle. Like I said, I’ve built other large frame 308s, but all of them had 18” - 20” barrels. While they were fun to shoot, they were quite nose heavy and cumbersome. @turnburglar, thanks for your input, getting 24” 308 performance out of a 16” gun firing a 130-140 grain projectile is basically what I’m looking to do. I’m also very encouraged by the 10.5 mils elevation out to 1k. Wilson Combat has a 16” 6.5 Creedmoor barrel with a 13.25” gas system that looks like a good candidate for what I’m looking to do.

    As far as receiver set, Mega Maten used to be my go to for AR10 type builds, but they’ve become a bit scarce. If I find another Maten set at a decent price (once I’m gainfully employed again), I wouldn’t mind snatching it up. My only complaint with Mega is that they’re kind of heavy. I did use a ZEV 308 receiver set for my last AR10, and they were excellent in all aspects except for price. I’m also kind of impressed with Wilson Combat’s 308 receivers, I like their clean simple looks. Aero Precision makes decent stuff, but the tolerances on all their receivers tend to run a bit too loose for my tastes.

    The build I have in mind goes like this: 308 receiver set (Mega, Zev, or Wilson Combat), LMT 308 carbine receiver extension, Armalite AR10 action spring, H3 buffer, Forward Controls QD end plate, B5 SOPMOD stock, Geissele SSA-E trigger, A2 grip, PRI Gas Buster charging handle, Wilson Combat bcg, Wilson Combat 16” barrel, Keymo flash hider, KAC 13” URX 4 handguard, KAC buis.
    Last edited by Hammer_Man; 06-21-22 at 11:59.

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    I am in the same boat and have everything to build a 14.5 6.5CM, except for the barrel. Criterion is supposed to be making their CORE barrels in 6.5CM, but have been sitting on them for over two years, using COVID as their excuse, and then just recently released the .300BO CORE barrels. I know they are planning on making them in 14.5, 16" and 18", but I am getting really impatient and want to build this gun, so I will probably have one cut to my specs using a JP barrel extension and Wilson intermediate length gas tube, because it is the closest to the KAC length gas tube (13.25 v. 13.35). I am using a Centurion MK11 receiver set, Centurion 7.62 M-LOK CMR, LMT .308 parts kit, LMT Carbine Extension, Sprinco Orange spring, H2 buffer, Fulton Armory Bolt Carrier, JP High Pressure Bolt, Centurion AST Trigger, Magpul PRS Lite stock, and a mix of Badger, FCD and Radian parts.
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    I piece of advice I've never forgotten in precision/LR...long enough ago that it was in regard to shorty 308's vs shorty 260/6.5x47's:

    "Velocities aside, pushing a better bullet is still pushing a better bullet"

    Meaning: that while not a peak efficiency, you can still eek some advantage out of the higher BC bullets even at lower velocities. Whether those gains are worth the cost/barrel/life/terminal effect penalties is the question posed to the individual.

    Personally, I was rather disappointed in the numbers I was getting out of 140gr 6.5CM from a 20" LMT MWS but it shot very well for what it was. Were I going to go any shorter (and I'd not stray 18-16.5 range), I would not even think about shooting anything over 130 and would probably try to figure out something with that 123gr Scenar projectile to buy back some speed without a significant cut in BC potential.

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    Quote Originally Posted by pointblank4445 View Post
    I would not even think about shooting anything over 130 and would probably try to figure out something with that 123gr Scenar projectile to buy back some speed without a significant cut in BC potential.
    If using 123 grain or lighter projectiles I wonder if 6.5 CM is worth the bulk over 6.5 Grendel, especially if center of gravity is a motivating factor as one could get away with a somewhat longer barrel on the AR-15 action.

    The 142 grain load is in another league however as in that weight the bullets eat up the limited Grendel case capacity.

    RifleShooter.com shows 120 grain Creedmore trending toward about 2600 fps from a 16" barrel.



    With an 18" Grendel barrel Andy Hobein averaged as much as 2534 fps with Federal ammunition. Other brands were slower.



    Last edited by Disciple; 06-21-22 at 15:45.

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