The 6.8 Remington Special Purpose Cartridge (SPC) and 6.5 Creedmoor are two centerfire rifle rounds that were developed for drastically different purposes.

The 6.5 Creedmoor (or 6.5 CM for short) was initially developed for competitive long range shooting while the 6.8 SPC was developed by the U.S. military to increase the lethality of the AR-15 platform and replace the 5.56 NATO.

Although the 6.8 SPC is inferior to the 6.5 Creedmoor in virtually every ballistic category, it is a hard-hitting semi-auto round that is effective against whitetail and hogs at closer ranges.

This leads many new shooters to question if they should invest in a bolt-action 6.5 Creedmoor hunting rifle or if a 6.8 SPC is good enough for their area.

In this article, we will evaluate the 6.5 Creedmoor vs 6.8 SPC to help you understand the differences between the two and give you a clearer idea of which cartridge is best for your shooting needs.

What is the difference between 6.5 Creedmoor and 6.8 SPC?

The primary difference between the 6.5 Creedmoor and 6.8 SPC is their intended rifle and use. The 6.5 Creedmoor was designed for use in bolt-action rifles for long range shooting competitions while the 6.8 SPC was designed to increase the power level of the AR-15 carbine.

Cartridge Specs

When evaluating centerfire cartridges, it's a good idea to analyze the cartridge specs to gain more knowledge of each.

Perhaps one of the biggest differences between the 6.8 SPC and 6.5 Creedmoor is how they came into being and their intended purpose.

The 6.8SPC is the elder of the two rifle cartridges being released in 2004 as part of a joint effort between Remington Arms, US Special Operations Command (USCOCOM), and the U.S. Army Marksmanship unit.

The round was developed by modifying the lesser known 30 Remington cartridge to fit into a standard M4 magazine and accept a 0.277" bullet diameter.

On the other hand, the 6.5 Creedmoor was released in 2007 in part due to a gripe session between legendary Service Rifle competitor, Dennis DeMille, and Dave Emary, the senior ballistician for Hornady Ammunition at the time.

The round was developed by necking down a 30 Thompson Center case to accept a 6.5mm or 0.264" bullet diameter.

In terms of bullet weight, the 6.5 Creedmoor will generally fire heavier bullets. The 6.8 SPC can fire bullets between 85 and 140 grains, however the 110 and 115 grain bullets are the most popular. In contrast, the 6.5 Creedmoor can fire bullets between 95 and 153 grains with the 120, 130, and 140 grain options being the most prevalent.

Perhaps one of the most striking differences between these two rounds is the massive difference in size. The 6.5 Creedmoor simply towers over the 6.8 SPC in terms of case length and overall length.

The 6.5 CM case measures 1.92" long with an overall length of 2.825" compared to 1.687" and 2.26" for the 6.8 SPC, respectively.

Although the 6.5 CM is the longer of the two cartridges, it is still short enough to fit into a short-action rifle. This is advantageous to the Creedmoor as short-action rifles are typically lighter and have a shorter bolt throw than standard action or long action rifles.

The 6.5 Creedmoor is a wider case as well with a base diameter of 0.470" compared to 0.422" for the 6.8 SPC.

These major differences in case dimensions means that the 6.5 Creedmoor will have a substantially higher case capacity than the 6.8 SPC. The SPC has a capacity of 34.8 gr but the 6.5 CM can hold a whopping 52.5 grains of powder. This means that the 6.5 Creedmoor can hold nearly 50% more powder than the 6.8SPC.

The final difference between these two rounds is the maximum chamber pressure each cartridge is rate for based on SAAMI specs. The 6.8 SPC can withstand 55,000 psi while the Creedmoor can handle considerably more at 62,000 psi.

What Is the Difference Between 6.8 SPC and 6.8 SPC II?

Although the 6.8 SPC seemed to be a potent and elegant answer to the 5.56 NATO terminal performance issue, there were some problems with its implementation.

When you're looking to purchase a new upper receiver or barrel for 6.8, you might notice that the barrel is stamped as 6.8 SPC II. Many new shooters wonder what the difference between 6.8 SPC and 6.8 SPC II is, and the answer is in the design of the chamber.

The 6.8 SPC II chamber is designed to handle full-power 6.8mm SPC loads while the original 6.8 SPC chamber had a design flaw that could potentially cause pressure issues.

In their haste to bring the 6.8 SPC to market and capitalize the hype surrounding the new round, Remington botched the release of the cartridge with inaccurate chamber design specifications.

The original chamber designs called for 0.050" of free bore. However, when combined with a 1:10 twist rate barrel, pressure issues began to creep up. Initial reports claimed that the rounds were only around 200 psi above the maximum 55,000 psi pressure limits, but if the military learned anything from Vietnam, it was to follow specs to the letter.

Remington sought to remedy the higher pressure issue the best way they saw fit, which was to underload the ammo instead of fixing the free bore measurement. The resulting "light" 6.8 SPC ammo failed to meet expectations, and the US Army scrapped the project.

However, in all the excitement over the new 6.8 SPC, several civilian firearm manufactures clambered to release rifles chambered in the new cartridge before SAAMI had officially standardized the 6.8 SPC round. With numerous faulty rifles in circulation, the only action SAAMI could take was to sanction the round.

This is not to say that original 6.8 SPC rifles won't function properly, but there is the potential for a critical pressure failure when using full power rounds.

The answer was the 6.8 SPC II.

The 6.8 SPC II added an additional 0.050" of free bore to the chamber and decreased the barrel twist rate to 1:11. This completely resolved the pressure issues experienced with the original design. All current rifles chambered in 6.8 SPC are technically chambered in 6.8 SPC II.

Although most factory loads will be loaded light (due to potential liability issues of original 6.8 SPC rifles still running loose in the wild), ammo for 6.8 SPC II rifles can be loaded to the full potential that the round was designed for.

To read more about the 6.8 SPC, check out these articles:

6.5 Grendel vs 6.8 SPC

Recoil

The 6.8 SPC will generally have less recoil than the 6.5 Creedmoor.

Recoil is an important consideration when purchasing a new rifle as a round with heavy recoil will be more difficult to control and will slow your rate of follow up shots. The potential for flinching is also an issue for cartridges with heavy recoil.

Free Recoil is affected primarily by muzzle velocity (FPS), powder charge, bullet weight, and firearm weight.

A true "apples-to-apples" comparison is not possible with these rounds as they are fired from drastically different firearms. The 6.5 CM is primarily fired from bolt-action rifles while the 6.8 SPC is fired exclusively in the AR-15 (currently).

The test firearms for this comparison will be the Savage 110 High Country for the 6.5 Creedmoor weighing 8.5 pounds and the LWRC Six8-A5 for the 6.8 Remington SPC weighing 7.25 pounds.

The cartridges in question will be the Hornady 143 gr ELD-X Precision Hunter for the Creedmoor with a muzzle velocity of 2,700 fps and the Hornady 120 gr SST with a muzzle velocity of 2,460 fps for the 6.8.

Given these criteria, the 6.5 Creedmoor will have 14 ft-lbs of free recoil compared to 8 ft-lbs for the 6.8 SPC.

That's nearly a 2x difference!

It should be noted that most shooters will not have a problem controlling the recoil of either round. The 6.5 Creedmoor is considered very low recoil for the ballistic performance offers when compared to other higher recoil competition rounds like the 308 Winchester or the 300 Win Mag.

However, for recoil sensitive shooters, the 6.8 SPC is clearly has less recoil and will allow for faster follow up shots than a 6.5 Creedmoor.

Muzzle Velocity, Kinetic Energy, and Trajectory

If you frequent any shooting or hunting forums, you are likely aware that proponents of the 6.5 Creedmoor proclaim that the round is perfect for all your shooting needs (just ask them). On the other hand, 6.8 SPC supporters like to point out the rounds low recoil and amazing short range terminal ballistics.

To evaluate these claims, we will compare four of the most popular factory loads on the market and see how they stack up against each other!

For this comparison, we will analyze two popular options for each cartridge. For the 6.5 Creedmoor we will analyze the Hornady 143 gr ELD-X and the Barnes VOR-TX 127 gr LRX polymer tipped bullet and for the 6.8 SPC the Hornady 120 gr SST and Federal 115 gr Fusion soft point (SP) were selected.

The rounds will be compared out to 500 yards with one additional data point at 800 yards to evaluate long range trajectory.

Continue reading 6.8 SPC vs 6.5 Creedmor here.