As an Amazon Associate I earn from qualifying purchases.
Our Associate portal can be found here
The first way to look at it is that a.308 Winchester is the starting point for the 6.5Creedmoor round, which means it will be possible to close the bolt if a 6.5Creedmoor round is in a .308 chamber. The reason is that the 6.5Creedmoor is shorter than the .308 and therefore, the shoulder will not be in contact with the forward end of the chamber. Also, the narrower neck and bullet will feed into the throat. As long as the round is supported at the bolt face, you can fire the round.
However, it is not among the best ideas to fire 6.5Creedmoor cases to .308 rifles. Even though it is a common technique typical for wildcat approaches where shooters create new cases from different sized parent cases.
If you consider the pressure curve, the 6.5mm bullet will not form a seal at the throat, and odds are that it would simply bounce down the barrel, or tear up the rifling as it fires. You might get some seal if the base of the bullet catches a groove as this will allow the pressure to deform it creating a crude seal. As a result, the bullet would be acting like a smoothbore ball. There will be no accuracy or stable flight trajectory.
No Need to Attempt
One of the appeals of 6.5Creedmoor is that the only part you need to change for you to use it on a .308 rifle is the barrel. It is to make the barrel on a .308 to have a compatible bolt and magazine. With this in mind, then the question is counterproductive hence no need to fire 6.5Creedmoor out of a .308 chamber.
You should never try to chamber or fire a case in a firearm that it is not designed to fire it even if the round fits and the bolt closes. You should never use close calibers interchangeably in guns that are not designed to fire them.
The result can perhaps be a breech-loading smoothbore with a wrecked barrel. Or the worst is a destructive pressure spike from the unpredictable nature of the case, bullet and the gun disassembled. Even the most curious shooters should avoid playing Russian Roulette with cases that can misfire in front of your face.
Can I Shoot .308 ammo out of a 6.5 Creedmoor Rifle?
The reverse is even more devastating. Unless you want to blow up your rifle or and seriously injure yourself and anyone close by then you can try. You may even die from fatal wounds. A 6.5 Creedmoor bullet is 0.264 inches in diameter whereas a .308 is just that, 0.308 inches in diameter. The difference is quite significant and the round would not even go in the chamber. It is more dangerous if you are firing from a bolt action rifle as it will probably send the bolt out the back of your head.
If you use the .308 in a 6.5Creedmoor chamber it will not close the bolt and it will jam in the throat of the chamber and as the case head sticks out. It is not even possible to hammer the bolt and sufficiently get it into battery position to pull the trigger.
Regardless, the 6.5Creedmoor and .308 are based on similar case dimensions but that is where the similarities end.
Which is Superior: The .308 vs 6.5 Creedmoor
The .308 case is a decent performer, but it is not the pinnacle for shooting at long range. If you take the shot Within 400 yards, the result will split hairs to most shooters. However, the drop between the 6.5 Creedmoor and 308 Winchester, the 6.5 Creedmoor rounds will offer better resistance to wind drift. If you further increase the distance to say 700-1000 yards, then the 6.5 Creedmoor will offer a substantial advantage in hit probability.
While the 6.5 Creedmoor somewhat resembles the .308 Winchester, it is more of a copy to the.30 TC case. It is worthy of noting before you reload your 6.5 Creedmoor. Another case difference is that the 6.5 Creedmoor has a sharper shoulder inclined at 30-degrees while the .308 Winchester has a 20-degree shoulder. This slight difference will make brass of a 6.5 Creedmoor last longer however, it will feed more reliably in a semi-automatic for the .308.
There is a surprising selection of bullets for the 6.5mm rifle. Bullet selection comes down to what a shooter finds useful when considering the case design. In a .308 Winchester, bullets in the 170+ grain size are hard to load to magazine limitations and also challenging to get enough power and speed out of. For instance, using the Sierra Matchking .308, a 175 grain can get a speed of 2600 feet per second. Compare that to the 6.5 Creedmoor, which sends a 140-grain bullet out at 2710 fps.
It means the Creedmoor sends a ballistically superior bullet at far higher speeds than the .308Winchester. Even if the .308 has more availability, the 6.5 Creedmoor uses ballistically better bullets. The bullets drop less and drift less in the wind.
When hunting big game, both cartridges are quite similar and will effectively do the job. However, some different models have a sharper point than others and will, therefore, have more penetration. Regardless, there are plenty of hunting bullets for both the 6.5 Creedmoor and the .308Winchester.
If you want to hunt big game at longer ranges, the difference in range between the 6.5 and .308 are not worth worrying about. But you should know the 6.5mm bullets will have a better Sectional Density-more lead behind a less surface area- compared to the .308 bullets. It is what makes them have a superior penetrating potential.
It is a clear win for the .308 Winchester as it is available in pretty much any bolt action rifle style that might interest you. The 6.5 Creedmoor is gaining more favor and coming up with more rifle models, but it is not anywhere near the .308 rifle selection and variety.
The Ruger Precision Rifle is offered in both .308 and the 6.5 Creedmoor. There is much curiosity to see how much it bolsters the popularity of 6.5 Creedmoor. For precision shooters, the rifle is an ideal entry rifle for long-range shooting. It automatically makes the 6.5 Creedmoor the ideal cartridge of choice for it due as it has superior long-range ballistics.
When firing lighter bullets, like the 6.5 Creedmoor, you will have less recoil than a rifle of the same weight in a .308 Winchester. The reason is because of the short action, and this will give the 6.5 Creedmoor a chance at unseating other popular calibers like the 7mm-08 and 243 as the low-recoil cartridge of choice.
The combination of higher speeds and a smaller bore does not augur well and eventually, the 6.5 Creedmoor will have a shorter lifespan than a comparable barrel in .308. However, the difference is not so significant and there will not be a ridiculous overbore. So it should not be too terrible.
Even though it is a win for the .308. If you are an experienced hunter this is just another minor factor. However, if you shoot a lot and participate in competitions then you should factor in the barrel life. The best estimate given for a .308 rifle is 5,000 rounds while that one for the 6.5 Creedmoor is only 2,000 to 2,500 rounds. This is only for first-class, competition-type, and accuracy.
In history, the .308 and 6.5 Creedmoor are two of the most accurate rounds in existence. In a short distance, the difference is highly noticeable, but at extreme long range, you could give the edge to the 6.5 Creedmoor. It is the easiest to shoot accurately.
Neither cartridge has any tricks of the trade, peculiarities, quirks, or hidden pitfalls. The 6.5 Creedmoor has an advantage since it accommodates very long bullets without that does not intrude into the powder space.
Realistically, there is more availability for low-cost ammo for the .308. The reason is that most hunters look for cheap and surplus ammo for practice. But when looking for a high-quality match or hunting ammo, the costs can be similar or slightly lower for the 6.5 Creedmoor.
If the 6.5 Creedmoor continues to gain in popularity as is the case, it may be a challenge to find them as stores will develop issues in keeping stock. The bottom line is that 6.5mm bullets cost less to ship and use less material therefore they will be cheaper to buy than .308 bullets.
Most Popular Rifle Accessories
We have an article on the best scopes for .308 rifles that you should check out. Also here is an accessories table to consider.
Despite the rising popularity of the 6.5 Creedmoor rounds, the .308 is not going anywhere anytime soon. The 6.5 Creedmoor is a great round, but it will be long before it completely overshadows the .308. Either way, they are rounds that are fun to shoot and will serve you well.
But the only principle to stay safe is never to shoot a caliber from a firearm that it was not designed to fire from. The results can be devastating and damaging your rifle barrel.
Amazon and the Amazon logo are trademarks of Amazon.com, Inc, or its affiliates.
36 years old, been hunting and fishing my entire life – love the outdoors, family, and all kinds of hunting and fishing! I have spent thousands of hours hunting hogs and training hunting dogs, but I’m always learning new stuff and really happy to be sharing them with you! hit me up with an email in the contact form if you have any questions.