.308 Winchester vs. 6.5 Creedmoor

The AR world's been flooded with new calibers, and relatively recently, the 6.5 Creedmoor round has become a popular choice among shooters building an AR-10 (really, an LR-308). What's the difference between these two loads? Is Creedmoor truly a high-performer that outclasses .308 Winchester? Here's our detailed comparison.

The .308 Winchester

The .308 Winchester's NATO partner, 7.62x51mm, was the first round to grace the chambers of Eugene Stoner's ArmaLite Rifle, the AR-10, before 5.56 NATO and the AR-15 were developed. This old military round was developed in the 1950s, when the U.S. military wanted a smaller cartridge that performed similarly to the .30-06, made famous by the M1 Garand during the war. This new round was made to fit in a smaller, lighter battle rifle, allowing troops to maneuver more easily. The experimental rifle which played host to the first .308 Winchester loads (officially titled '7.62x51mm' by NATO), the T44, would later become the M14. 

Physical Specs

• Bullet diameter: 0.308" (7.8mm)
• Case length: 2.015" (51.2mm)
• Parent case: .300 Savage
• Case capacity: 56 gr H2O 
• Max pressure (SAAMI): 62,000 psi
• Base diameter: 0.4709" (11.96mm)
• Rim diameter: 0.4728" (12.01mm)

7.62x51 NATO vs .308 Winchester

The 7.62 cartridge was officially adopted by the military in 1954. But the Winchester Repeating Arms company saw opportunity in offering this new cartridge to the civilian market for hunting and competition. As such, the company developed their own version of the NATO load, aptly named the .308 Winchester, and introduced it in 1952. The civilian variant of this cartridge is only slightly different from the NATO load. It utilizes thinner brass with headspaces measuring 1.630" to 1.634", while NATO uses 1.6355" to 1.6405" headspace. The two cartridges are similar enough, however, that they may be safely cross-loaded in any .308-caliber rifle.

The 6.5 Creedmoor 

The 6.5 Creedmoor round was developed by Hornady in 2007. Based on the .30 Thompson Center (a derivative of .308 Winchester) this thin, fast load was designed for long-range shooting and competitions for Creedmoor Sports. Utilizing a 30-caliber casing with a smaller 0.264" bullet provides two benefits that make Creedmoor a high-performer: The 6.5mm bullet maintains a high sectional density, which measures the distribution of the mass of an object along its axis to overcome resistance. The case's high volume relative to its bore area also allows loading these long, slender bullets in front of quite a bit of powder. The result is high velocity and a high ballistic coefficient (BC) at greater distances. 

Physical Specs

• Bullet diameter: 0.264" (6.72mm)
• Case length: 1.920" (48.8mm)
• Parent case: .30 TC
• Case capacity: 52.5 gr H2O 
• Max pressure (SAAMI): 62,000 psi
• Base diameter: .4703" (11.95mm)
• Rim diameter: .4730" (12.01mm)

308 Win vs. 6.5 Creedmoor Ballistics

Both cartridges maintain relatively similar physical specifications. Each has the same max pressure, nearly identical casings and diameters, similar overall case capacities, and similar overall lengths, allowing both loads to fit in a short action like the AR-10 and LR-308. While 6.5 Creedmoor's bullets are about 15% thinner, some heavier loads are available that approach the same grain weights as .308 Winchester. 

So, how do these two stack up against each other downrange?

Bullet Drop

The data below were collected at intervals of 200 yards to 1,000 yards. With bullet drop we're comparing 130-grain 6.5 Creedmoor rounds to 175-grain .308 Win rounds, which are Sierra Match Kings:

Under 500 yards, .308 Winchester only drops about 4" more than 6.5 Creedmoor. At 600 yards to 1,000 yards, though, Creedmoor's performance begins to shine. Winchester begins dropping by more than a foot, and winds up dropping three feet more at max distance. The difference increases from 13% at 200 yards to 23% at 1,000 yards.

Drop & Drift at 1,000 Yards

Both rounds are capable of providing good accuracy at 1,000 yards. But with distance comes loss in velocity, and with loss in velocity comes greater affects imparted on the round by wind and bullet drop. Let's see how these two rounds stack up at the extreme end. The same 140-grain Berger bullet is utilized with these data to give a better direct comparison.

6.5 Creedmoor

• Velocity: 1,370 FPS
• Bullet drop: 349"
• Wind drift (5 mph): 39.18"

.308 Winchester

• Velocity: 1,203 FPS
• Bullet drop: 386"
• Wind drift (5 mph): 48.53"

Overall, The 140-gr Berger retains 13.8% more velocity at 1,000 yards when loaded in the Creedmoor. It drops just over three feet less, or about 9.5" less than Winchester, too. It drifts 9.3" less, or about 19.3% less. At 1,000 yards these numbers are somewhat significant, especially accounting for three feet of drop. So, at the far end of what most variable optics and most "stock" rifles can do, Creedmoor beats Winchester handily. But most shooters don't shoot at these distances often, if at all. And, at this distance, other factors like barrel length, barrel and action bedding, and trigger pull can play a bigger role than ballistics alone. Let's look at performance at more manageable range of 500 yards.

500 Yard Performance

Now that we've seen how Winchester stacks up against Creedmoor in a 1:1 comparison at the extreme end, let's look at something more realistic, or at least, more common: Shooting at 500 yards with optimized loads for both cartridges. In this data, comparing a 135-grain 6.5mm with a more common 168-grain .308 Sierra Match King to achieve better a ballistic coefficient for the latter.

6.5 Creedmoor

• Velocity: 1,954 FPS
• Bullet drop: 57"
• Wind drift (5 mph): 8.3"

.308 Winchester

• Velocity: 1,824 FPS
• Bullet drop: 60.5"
• Wind drift (5 mph): 10.4"

Winchester gets much more competitive at this range, but Creedmoor still maintains a slight edge. The 6.5 CM yields about 7% more velocity, about 6% less drop, and most of all, 20% less wind resistance. At this distance, though, the real-world figures aren't dramatic. Creedmoor only drifts 2" less off point of aim, and it only drops 3.5" less. Both figures can be easily compensated for with either loads.

Factors Besides Performance

Barrel Life

The .308 Winchester's known for being relatively forgiving when it comes to barrel life. Even with semiautomatic fire, most shooters say acceptable long-range accuracy can be had for up to 10,000 rounds. Most shooters averaging sub-MOA accuracy report they're able to maintain tight groupings up to 4,000 to 5,000 rounds. This is most certainly not the case when it comes to 6.5 Creedmoor. 

In fact, Creedmoor runs so hot that you can expect your barrel to lose that 1,000-yard laser touch at around 2,500 to 3,000 rounds. Thanks to Creedmoor's high ballistic coefficient and physical shape, accuracy can be maintained with consistency above 2,000 rounds, but shooters have reported losing up to 100 or more feet per second in velocity around this point. This will translate into noticeably more bullet drop and compensation at greater distances. Of course, heat and your rate of fire play a major factor in barrel life. If you're taking your time between shots and running your barrel relatively cool, you can squeeze out quite a bit more barrel life. Many have reported being able to approach 3,500 to 4,000 rounds.

But you may opt to shoot Creedmoor in the AR platform instead of a slow bolt gun. If that's the case, you might find yourself wearing out that barrel in surprisingly short order. Such is the cost of achieving hyper accuracy in a semiautomatic rifle with a fast round with a high ballistic coefficient.

Winner: .308 Winchester.

Ammo Cost

Winchester's been a favorite among hunters and bench rifle owners for about five decades. It's produced by dozens, if not hundreds, of manufacturers and Sierra Match King and other high-end loads can be grabbed with relative affordability. As this writer compares price per round in early 2021 on Ammoseek, the cheapest .308 Winchester brass comes in at $0.90 per round. Match-grade loads come in at around $1.25 to $1.50.

The cheapest Creedmoor rounds start at $2.50 per round, climbing up to $3.50 to $4.00 for match loads. That translates into a 20-round box of 6.5mm for at least $50 to $75, compared to just $18 for a box of 20 Winchesters. When you consider that you can still find "spam cans" of 7.62 NATO to bring costs down on bulk ammo purchases, the value found in .308 is even greater. If you like to shoot often and perform the occasional mag dump, Winchester will be easy on both your barrel and your wallet. Creedmoor, not so much.

Winner: .308 Winchester.

The Rifle

Because Creedmoor and Winchester are so similar, it's easy to find your favorite bolt gun or AR rifle for either load. In fact, 6.5 Creedmoor is specifically made to fit in the .308 AR platform without any modification, save for the barrel. It uses .308 upper and lower receivers, the same parts kit, even the same magazines. To ensure your rifle doesn't get beat up, you'll need to invest in a "high-pressure" bolt and firing pin, which  our 6.5 Creedmoor AR kits come with.

Recap

You should now have a good idea of which load will better suit your shooting needs when it comes to 6.5 Creedmoor vs. 308 Winchester. Let's recap some of the most important things:

• Creedmoor is a 6.5mm cartridge developed for long-range shooting.
• Winchester's .308 cartridge id based on the military's 7.62 NATO round.
• Creedmoor provides 7% to 12% more velocity between 500 and 1,000 yards.
• Winchester suffers from approximately 20% more wind drift at 1,000 yards.
• A Winchester barrel will typically last about 10,000 to 15,000 rounds.
• A Creedmoor barrel can be shot out in as few as 3,000 to 4,000 rounds.
• The average Winchester round costs $0.90 to $1.50.
• The average Creedmoor round costs $2.50 to $4.00.
• Both loads fit in the LR-308, DPMS' version of the AR-10.