Short(er) Barrel 6.5 Creedmoor?

[El Cid]

Has anyone messed around with 6.5 Creedmoor in shorter barrels? Most of the options I see are 18 inches and longer. There are some 16” options, but the only one below that I can find is a 14.1” from Ballistic Advantage. I’m toying with a build that would be on the shorter side. Most likely a pin and weld since going the NFA route means it can’t leave the state without a permission slip. I don’t have anywhere to shoot really long distance anyway, and if I did I could always build an upper with a longer barrel.

Everything I’ve read says that 6.5CM from a 14.5 or 16” barrel still outperforms .308 from longer barrels. This is a long-term project so maybe I just wait and let the market catch up? BA certainly makes nice barrels, but I like having options and would prefer a factory barrel over having one cut down.

Thoughts? Anything I’m missing?

Thanks!

[Skinner Precision, LLC]

Has anyone messed around with 6.5 Creedmoor in shorter barrels? Most of the options I see are 18 inches and longer. There are some 16” options, but the only one below that I can find is a 14.1” from Ballistic Advantage. I’m toying with a build that would be on the shorter side. Most likely a pin and weld since going the NFA route means it can’t leave the state without a permission slip. I don’t have anywhere to shoot really long distance anyway, and if I did I could always build an upper with a longer barrel.

Everything I’ve read says that 6.5CM from a 14.5 or 16” barrel still outperforms .308 from longer barrels. This is a long-term project so maybe I just wait and let the market catch up? BA certainly makes nice barrels, but I like having options and would prefer a factory barrel over having one cut down.

Thoughts? Anything I’m missing?

Thanks!

Bolt gun=no problems. Gas gun = challenges and compromises. If your gun plumber makes the challenge/compromises work, you will end up with wicked port erosion at a relativelyly low round count. 6.5 creeds run hotter than 308 win and the port pressures are significantly higher.

I would recommend sticking to 16" minimum in a creed but the heart wants what the heart wants...

[El Cid]

Bolt gun=no problems. Gas gun = challenges and compromises. If your gun plumber makes the challenge/compromises work, you will end up with wicked port erosion at a relativelyly low round count. 6.5 creeds run hotter than 308 win and the port pressures are significantly higher.

I would recommend sticking to 16" minimum in a creed but the heart wants what the heart wants...

That’s not even something that was on my radar - thanks! So 16” gas guns are good to go? Part of wanting to go short is that it will have a can on it.

[Skinner Precision, LLC]

That’s not even something that was on my radar - thanks! So 16” gas guns are good to go? Part of wanting to go short is that it will have a can on it.

16" you can "get by" with a rifle length gas system. 14.5" is going to force you to an intermediate system. Even 20/22" creeds sometimes have trouble with the pressure of Hornady factory ammo depending on how they are set up. Dwell Time , Port Pressure and Peak Pressure all play in the balancing act I mentioned above. 16" isn't a drama free equation but 14.5" gets you more drama and a narrower operating window. I am getting ready to spin a dedicated short range hunter AR 10 creed barrel for myself from a low mile tikka takeoff, it will have a can and I can do my own pin and weld but I am taking my own advice and keeping it 16". Note since it is essentially a free barrel to me, I don't care about the port erosion and if the barrel is trashed before it is shot out... If short/suppressed is driving the mission, I would look at 308 with a 13.7-14.5" 308 Win my biggest concern would be- is if the can I use is rated for it, a lot of "legacy" cans were only rated for 16" and it impressive how much the uncorking pressure goes up as the barrel gets short, IRC 26" is under 2KSI but 16" is around 10KSI

[El Cid]

16" you can "get by" with a rifle length gas system. 14.5" is going to force you to an intermediate system. Even 20/22" creeds sometimes have trouble with the pressure of Hornady factory ammo depending on how they are set up. Dwell Time , Port Pressure and Peak Pressure all play in the balancing act I mentioned above. 16" isn't a drama free equation but 14.5" gets you more drama and a narrower operating window. I am getting ready to spin a dedicated short range hunter AR 10 creed barrel for myself from a low mile tikka takeoff, it will have a can and I can do my own pin and weld but I am taking my own advice and keeping it 16". Note since it is essentially a free barrel to me, I don't care about the port erosion and if the barrel is trashed before it is shot out... If short/suppressed is driving the mission, I would look at 308 with a 13.7-14.5" 308 Win my biggest concern would be- is if the can I use is rated for it, a lot of "legacy" cans were only rated for 16" and it impressive how much the uncorking pressure goes up as the barrel gets short, IRC 26" is under 2KSI but 16" is around 10KSI

Thanks! I already have a 16” 308 gasser. I’ve wanted to try out 6.5CM for a while and snagged a large frame receiver set this past weekend.

Good to know about the cans. My plan was just to use a HUX flow through can. Have those had the same issues? Hopefully the gas venting out the front alleviates some of the concern?

[Skinner Precision, LLC]

Thanks! I already have a 16” 308 gasser. I’ve wanted to try out 6.5CM for a while and snagged a large frame receiver set this past weekend.

Good to know about the cans. My plan was just to use a HUX flow through can. Have those had the same issues? Hopefully the gas venting out the front alleviates some of the concern?

By uncorking pressure I am referring to the pressure of the gas at the end of the muzzle, the longer the barrel- the more opportunity for the gas to be consumed in the barrel- it's why 7.5" 5.56 are so "blasty", the pressure at the muzzle is more. It is a function of barrel length.

I am unfamiliar with an easy way to measure the pressure at the muzzle beyond estimating it via software simulation, quickload being one of the cheapest /most availibleto the average person.

Any can needs to be a strong enough pressure vessel to contain the pressure (hopefully with a comfortable safety factor) and made of materials that resist the abrasive of the hot gas/unhurt powder.

A flow through can like the the HUX reduces the backpressure of gas vented back through the action as it cycles. Even though we callnit backpressure as an analogy to ICE it is really a gas volume not a pressure issue

[JRB]

I'm really curious what you mean by 'outperforms' when you say that a short 6.5 Creed 'outperforms' .308 from shorter barrels.

By all my experience and understanding, 6.5CM is much happier and optimized for longer barrels for the sake of cartridge efficiency. A narrower projectile like the 6.5CM needs more time (read: barrel length) to take advantage of its higher pressures vs a .30 cal.

If you were hot and bothered for SBR length barrels I can't imagine a worse cartridge than 6.5CM to set up for - with the possible exception being that 6.5CM loads are generally very consistent so if you do get something dialed in to run on a narrow operating window, chances are much higher that your gun will run with a variety of ammo.

But if I'm doing an AR-10ish SBR, I'm going .308/7.62 NATO down to about 12.5in at most. Any shorter than that and I'll just do .300 BO or 7.62x39 instead and enjoy much less recoil and muzzle flash for near-as-makes-no-difference terminal ballistics.

6.5CM? I wouldn't bother with less than 20in, let alone 16in. Kneecapping a flat shooting high velocity high pressure cartridge with a too-short barrel is just a recipe for mediocrity.

[texag]

I'm really curious what you mean by 'outperforms' when you say that a short 6.5 Creed 'outperforms' .308 from shorter barrels.

By all my experience and understanding, 6.5CM is much happier and optimized for longer barrels for the sake of cartridge efficiency. A narrower projectile like the 6.5CM needs more time (read: barrel length) to take advantage of its higher pressures vs a .30 cal.

If you were hot and bothered for SBR length barrels I can't imagine a worse cartridge than 6.5CM to set up for - with the possible exception being that 6.5CM loads are generally very consistent so if you do get something dialed in to run on a narrow operating window, chances are much higher that your gun will run with a variety of ammo.

But if I'm doing an AR-10ish SBR, I'm going .308/7.62 NATO down to about 12.5in at most. Any shorter than that and I'll just do .300 BO or 7.62x39 instead and enjoy much less recoil and muzzle flash for near-as-makes-no-difference terminal ballistics.

6.5CM? I wouldn't bother with less than 20in, let alone 16in. Kneecapping a flat shooting high velocity high pressure cartridge with a too-short barrel is just a recipe for mediocrity.

When do the advantages of a 6.5 creedmoor vs a .308win (shooting higher bc bullets at greater velocity with less recoil) disappear? Do they disappear at all?

[SecondsCount]

Why not just build a 6.5 Grendel?

I don't have one but shoot with a couple guys that do. One of them has a 12" barrel, and it does really well.

[Skinner Precision, LLC]

I'm really curious what you mean by 'outperforms' when you say that a short 6.5 Creed 'outperforms' .308 from shorter barrels.

By all my experience and understanding, 6.5CM is much happier and optimized for longer barrels for the sake of cartridge efficiency. A narrower projectile like the 6.5CM needs more time (read: barrel length) to take advantage of its higher pressures vs a .30 cal.

If you were hot and bothered for SBR length barrels I can't imagine a worse cartridge than 6.5CM to set up for - with the possible exception being that 6.5CM loads are generally very consistent so if you do get something dialed in to run on a narrow operating window, chances are much higher that your gun will run with a variety of ammo.

But if I'm doing an AR-10ish SBR, I'm going .308/7.62 NATO down to about 12.5in at most. Any shorter than that and I'll just do .300 BO or 7.62x39 instead and enjoy much less recoil and muzzle flash for near-as-makes-no-difference terminal ballistics.

6.5CM? I wouldn't bother with less than 20in, let alone 16in. Kneecapping a flat shooting high velocity high pressure cartridge with a too-short barrel is just a recipe for mediocrity.

If you stick to 140-147 class bullets I would agree that there is 350-400ish penalty from docking a barrel from 26-16" but if you stay with the 130 gr class of bullets' you only see a 200-250 fps deficit and you still have a bullet with more bc (130 SMK-.584, 130 ELD-M ..279 G7& berger 130 OTM .287 G7) than all but the heavy class of 30cal projectiles, way faster than a shorty .308 can throw them( 185 gr. Jugg to 200 gr low drag/high BC bullet). 16" 130 gr 6.5 @ 2650ish vs 185 gr 16"308 at 2350 is a closer comparison of the two cartridges performance envelope in a short barrel, and the 6.5 does it with less recoil.

My personal PRS rifle (.260 Rem) has a 29" Mueller on it , my boy's more dual purpose 6.5 creed has a 22" Lilja, what you are doing with it drives the choices that budget and availability do not.

The attached picture is what started out as a 24" Tikka CTR in 6.5. It belongs to client who is a serious coyote caller / hunter, he first had me chop his CTR after getting a can and disliking it in the field- he hunted with it for the rest of the season, loved the less then a KY Long Rifle feeling. Before the next season he got a hankering for something fancier so I put a new stock, trigger and carbon fiber wrapped Bartlien barrel on it , he could have had anything from 16-26" without much of a delta in the weight department. After having hunted this rifle at both 24" and 16.5" he choose 16.5" for the Bartlien without hesitation. Convenience for the 5-10 miles of walking he does per day hunting and calling far outweighed the ballistic advantage in this part of the midwest where 450-500 yd coyote shots are about the normal max.