308 vs 556 – 2022 Comparison

The .308 Win and 5.56 NATO are insanely popular rounds in their respective classes. While one is a reliable .30 caliber round, the other is the king of the .22 caliber ammo. Each of them has their own set of pros and cons, but they are undoubtedly among the most widely used, easily available, and trusted cartridges available today.

Which is why, it is very likely that a person who owns rifles will have guns chambered in these cartridges. This makes it important to understand whether you should choose one over the other when the need arises, or perhaps you should have both. Let’s find out. 

TL;DR: 308 vs 556

Here’s a concise table to give you an overview of the pros and cons of the .308 Win vs. the 5.56 NATO

308 Overview

The .308 Winchester is a rimless, bottlenecked, standard action cartridge that fires a .308 inch diameter bullet and has an overall length of 2.80 inches. It was introduced on the market in 1952 by Winchester as a replica of the experimental T65 cartridges being tested by the military to replace the .30-06 Springfield cartridges. 

The improved version of the T65, the T65E5 was adopted by the U.S Military as the 7.62×51 mm or 7.62 NATO round in 1954. While the chamber pressures for the .308 Win and 7.62 NATO differ a bit, technically both these rounds can be fired interchangeably. 

The .308 Winchester has been one of the most successful hunting cartridges on the market since its introduction. It is one of the most versatile rounds to ever exist and is used by hunters, marksmen, and police snipers. Rifles such as the Winchester Model 70 made the round very popular among the masses. Additionally, the .308 Win was labeled as the ideal cartridge by the late Col. Jeff Cooper and the favorite choice for scout rifles. 

The relatively short case of the .308 Win made it suitable for short actions, and hence for semi-automatic rifles. The earlier .30-06 Springfield rounds were bigger, bulkier, and had an unforgiving recoil. 

556 Overview

The 5.56×45 mm also known as the 5.56 NATO is a rimless, bottlenecked, intermediate rifle cartridge developed in the late 1970s by Belgium’s FN Herstal. It fires a 0.224 inches diameter bullet and has an overall length of 2.26 inches. The 5.56×45 mm was adopted by the NATO forces as their standard cartridge in 1980 and has since been the standard cartridge for all NATO and some non-NATO militaries. 

The 5.56 NATO was designed as a replacement for the 7.62 NATO rounds which were proving to be bulkier and with a heavier recoil. The usage of such heavy rounds was deemed unnecessary, especially during the Vietnam war when the battles were mostly fought in close quarters. 

The two most common variants of these rounds used by the military are M193 which uses a 55-grain projectile, and the M855 which uses a 62-grain projectile. The M855 and its advanced version, the M855A1 are the ones most prevalent today and used by the U.S Military. 

The 5.56 NATO is inspired by the .223 Remington which was already a popular sporting cartridge in the U.S market. Both these cartridges are almost the same with the only prominent difference being the chamber pressure. The 5.56 NATO is loaded at higher chamber pressures than the .223. So a .223 can be fired from a 5.56 NATO chamber, but the vice-versa is not possible.

The widespread popularity of the AR-15 platform made the .223/5.56 caliber insanely popular across the country. 

308 vs 556: Cartridge Specs

	308	556
Bullet Diameter	7.80 mm (0.308 in)	5.70 mm (0.224 in)
Neck Diameter	8.72 mm (0.343 in)	6.43 mm (0.253 in)
Base Diameter	11.96 mm (0.470 in)	9.58 mm (0.377 in)
Case Length	51.2 mm (2.015 in)	44.70 mm (1.760 in)
Overall Length	71.1 mm (2.80 in)	57.40 mm (2.260 in)
Case Capacity	56 grains	28.5 grains
Max Pressure (SAAMI)	62,000 psi	62,000 psi
Typical Casing Material	Brass or Steel	Brass
Typical Bullet Weight (gr)	150-180 grains	55-69 grains

The .308 Win is a bigger cartridge than the 5.56 NATO. It uses a larger diameter bullet of 0.308 inches compared to the 0.224 inches of the 5.56 NATO. The difference in size translates to obvious differences in the case capacity and bullet weights. 

The .308 Win has almost twice as capacity as the 5.56 NATO. Which is also important because it has to propel bullets that are almost thrice more in weight. Talking about the 5.56 NATO, the casing material is always brass and the most common bullet weights are 55 and 62 grains. There are other weight options as well, but they are not used very commonly. 

On the other hand, the .308 Win with its fatter case and slightly longer case length allows for bullet weights ranging from 150 to 180 grains. The 150, 168, and 180 grains are the most common ones in use, but there is a wide range to choose from which goes slightly beyond 200 grains. 

Both of these are standard length cartridges and can be easily cycled through semi-auto rifles. The .308 Win takes up more space and weight compared to the 5.56, but neither of these requires banana mags and can be fed from straight AR-style STANAG magazines. 

308 vs 556: Ballistics

The ballistics of a projectile covers the characteristics related to its movement and impact. The major factors studied under this are the trajectory, velocity, and kinetic energy of the bullet. These things help us understand how a bullet performs at a certain range and if it is suitable for any specific application. 

308 vs 556: Trajectory

Take a quick peek at the trajectory characteristics of the .308 Win vs the 5.56 NATO rounds. 

.308

24”barrel/BC 0.408/150 gr FMJ Boat-tail	24”barrel/BC 0.489/168 gr Berger Hybrid	24”barrel/BC 0.536/175 gr Edge TLR
100 yds: 0 “ Drop	100 yds: 0 “ Drop	100 yds: 0 “ Drop
200 yds: 3.6 “ Drop	200 yds: 4 “ Drop	200 yds: 4.4 “ Drop
300 yds: 13.5 “ Drop	300 yds: 14.4 “ Drop	300 yds: 15.5 “ Drop
400 yds: 30.6 “ Drop	400 yds: 32 “ Drop	400 yds: 34.2 “ Drop
500 yds: 56.3 “ Drop	500 yds: 58 “ Drop	500 yds: 61.5 “ Drop
1,000 yds: 405.5 “ Drop	1,000 yds: 384.2 “ Drop	1,000 yds: 392.5 “ Drop

5.56

9” barrel/BC .304/62 gr M855A1 Supersonic	16” barrel/BC .340/77 gr Ranger BTHP	20” barrel/BC 0.220/55 gr FMJ BT
100 yds: 0” Drop	100 yds: 0” Drop	100 yds: 0” Drop
200 yds: 4.2” Drop	200 yds: 3.4“ Drop	200 yds: 3” Drop
300 yds: 17.2” Drop	300 yds: 12.9” Drop	300 yds: 12.1” Drop
500 yds: 40.9” Drop	500 yds: 56.1” Drop	500 yds: 57.9” Drop

For our test data, I took the maximum range for a .308 Win to be 1,000 yards, compared to only 500 yards for the 5.56 NATO. The only reason behind this is their expected performance and maximum effective range. 

The .308 Win was designed to be a long range round and is capable of hitting targets out to 1,000 yards and even more. The 5.56 NATO due to its weight and size is mostly suitable out to a maximum range of 500 or maybe 600 yards.

The bullet weights selected for the comparison are the most common weights used for these rounds. Looking at the data, it is evident that the difference in the trajectory of both these bullets (in comparable weights) is not too much. A 150 grain .308 Win drops 13.5 inches at 300 yards, whereas a 5.56 NATO 55 grain bullet drops to 12.1 inches. 

So where’s the difference exactly? If the range in question is within 500 yards, and you are hitting paper or steel targets, there isn’t much of a difference in trajectory (which is not taking into consideration the wind drift of ballistic coefficient). However, if you are aiming for long range shots with lesser adjustments for elevation, the .308 Win is a clear winner. To give you a perspective, the .308 Win 150 grain drops about 405 inches at 1,000 yards, compared to the 556 inches drop for the 55 grain 5.56 NATO. 

308 vs 556: Velocity & Kinetic Energy

Let’s crunch some numbers regarding the velocity and kinetic energy characteristics of these bullets. This will help us understand the accuracy and maximum effective range characteristics.

.308

24”barrel/BC 0.408/150 gr FMJ Boat-tail	24”barrel/BC 0.489/168 gr Berger Hybrid	24”barrel/BC 0.536/175 gr Edge TLR
100 yds: 2,597 ft/s, 2,246 ft.lbs	100 yds: 2,518 ft/s, 2,365 ft.lbs	100 yds: 2,437 ft/s, 2,308 ft.lbs
200 yds: 2,385 ft/s, 1894 ft.lbs	200 yds: 2,343 ft/s, 2,048 ft.lbs	200 yds: 2,280 ft/s, 2,021 ft.lbs
300 yds: 2,183 ft/s, 1,586 ft.lbs	300 yds: 2,176 ft/s, 1,766 ft.lbs	300 yds: 2,130 ft/s, 1,762 ft.lbs
400 yds: 1,990 ft/s, 1,319 ft.lbs	400 yds: 2,015 ft/s, 1,514 ft.lbs	400 yds: 1,984 ft/s, 1,530 ft.lbs
500 yds: 1,808 ft/s, 1,089 ft.lbs	500 yds: 1,860 ft/s, 1,291 ft.lb	500 yds: 1,845 ft/s, 1,322 ft.lbs

5.56

9” barrel/BC .304/62 gr M855A1	16” barrel/BC .340/77 gr Ranger BTHP	20” barrel/BC 0.220/55 gr FMJ BT
100 yds: 2,308 ft/s, 733 ft.lbs	100 yds: 2,662 ft/s, 1,210 ft.lbs	100 yds: 2,837 ft/s, 983 ft.lbs
200 yds: 2,045 ft/s, 576 ft.lbs	200 yds: 2,405 ft/s, 988 ft.lbs	200 yds: 2,468 ft/s, 744 ft.lbs
300 yds: 1,802 ft/s, 447 ft.lbs	300 yds: 2,162 ft/s, 799 ft.lbs	300 yds: 2,128 ft/s, 553 ft.lbs
500 yds: 1,384 ft/s, 264 ft.lbs	500 yds: 1,722 ft/s, 507 ft.lbs	500 yds: 1,540 ft/s, 290 ft.lbs

The velocity data of the .308 Win showcases that the bullets will stay supersonic past 1,000 yards. Which means that accuracy and other factors for these rounds are more predictable and suitable for the long range. 

On the other hand, the 5.56 NATO bullets lose their supersonic ability at around 800 yards on average. Which is the maximum range out to which these rounds are recommended to be used. Comparing the .308 Win and 5.56 NATO for velocities, the .308 Win will mostly have an upper hand beyond 400 yards. However, within a range of 200 yards, the 5.56 NATO will mostly win because of the higher muzzle velocity. 

Now moving on to the power characteristics, the 5.56 NATO is practically useful for anything bigger than the size of a small deer. In fact, most states don’t even allow this round for deer hunting. With an average muzzle energy of about 800 fpe at 100 yards, the 5.56 NATO quickly plummets down with increasing range.

The .308 Win is an absolute powerhouse, especially when compared to the energy of 5.56 NATO. The heavier bullets retain around 1,500-foot pounds of energy at 400 yards, which is considered optimal to kill an elk-sized game. It is also a big reason why the .308 Win is considered a versatile round. 

308 vs 556: Stopping Power

The stopping power of a bullet describes its ability to stop or incapacitate a target as quickly as possible and with a minimal number of shots. Generally, bigger caliber bullets are expected to have better stopping power, but that is not always the case. The two most appropriate characteristics to measure this are the momentum and sectional density of a bullet. 

308 vs 556: Momentum & Sectional Density

The sectional density of an object is the ratio of its mass to its cross-sectional area. For a bullet, it describes the penetrating power and the size of the wound channel. So the higher the value, the more penetration, and damage will be delivered by the bullet. 

.308

24”barrel/BC 0.408/150 gr FMJ Boat-tail Sectional Density: 0.266	24”barrel/BC 0.489/168 gr Berger Hybrid Sectional Density: 0.253	24”barrel/BC 0.536/175 gr Edge TLR Sectional Density: 0.264
100 yds: 55 lb.ft-s	100 yds: 60 lb.ft-s	100 yds: 60 lb.ft-s
200 yds: 51 lb.ft-s	200 yds: 56lb.ft-s	200 yds: 57 lb.ft-s
300 yds: 46 lb.ft-s	300 yds: 52 lb.ft-s	300 yds: 53 lb.ft-s
400 yds: 42 lb.ft-s	400 yds: 48 lb.ft-s	400 yds: 49 lb.ft-s
500 yds: 38 lb.ft-s	500 yds: 44 lb.ft-s	500 yds: 46 lb.ft-s
1,000 yds: 24 lb.ft-s	1,000 yds: 26 lb.ft-s	1,000 yds: 27 lb.ft-s

5.56

9” barrel/BC .304/62 gr M855A1 Sectional Density: 0.177	16” barrel/BC .340/77 gr Ranger BTHP Sectional Density: 0.219	20” barrel/BC 0.220/55 gr Supersonic Sectional Density: 0.157
100 yds: 20 lb ft-s	100 yds:  29 lb ft-s	100 yds:  22 lb ft-s
200 yds: 18 lb ft-s	200 yds: 26 lb ft-s	200 yds: 19 lb ft-s
300 yds: 15 lb ft-s	300 yds: 23 lb ft-s	300 yds: 16 lb ft-s
500 yds: 12 lb ft-s	500 yds: 18 lb ft-s	500 yds: 12 lb ft-s

Let’s first talk about sectional density and how it must be measured. As a general rule of thumb, a sectional density (SD) of less than 0.210 is good for small game and varmints, an SD of 0.220 to 0.270 is suitable for deer-sized game, and an SD of 0.271 to 0.300 is great for class 3 elk sized game. Anything above 0.300 is suitable for thick-skinned Class 4 games. 

Some small caliber rounds, like the 0.264 and 0.284 can have an SD of more than 0.300, so they are more versatile. Some .308 Win loads can also have an SD greater than .300. 

Looking at our data, it is clear that the 0.308 Win is an amazing deer and elk round. This makes it very versatile and also great for inflicting more damage on smaller targets. On the other hand, the 5.56 NATO generally has an SD of less than 0.200 and will not penetrate as much. The smaller bullet size and FMJ design can cause it to wobble inside, but if it doesn’t, the wound channel will not be too big. 

Please bear in mind that the penetration we are discussing here is for objects, armor, cover, and game animals. The 5.56 NATO is a military cartridge, and interestingly, FMJ rounds are designed for wounding rather than killing. However, humans are fragile beings and do not take too much effort to incapacitate. 

Talking about momentum, it is the characteristic of a moving object to stay in motion, and the higher the value, the more difficult it will be to stop such an object. In other words, it also describes the level of energy transfer after the collision. 

.308 Win bullets carry as much momentum at 1,100 yards as a 5.56 NATO round carries at 100 yards. So .308 Win is a clear winner in terms of stopping power. 

308 vs 556: Use Cases & Effective Range

Both the .308 Win and 5.56 NATO are widely used cartridges and extremely popular among civilians as well as defense forces. Understand how each of these is extremely useful in certain situations:

Small or Big Game Hunting

Small game animals, pests, and varmints can be a nuisance for farm owners. Coyotes and hogs are exceptionally damaging to crops and if you have a farm infested with these, the 5.56 NATO will be the round of choice for its appropriate power, low cost, and controllability for consecutive shots. 

If you are considering hunting down anything bigger than a small hog or coyote, the .308 Win should be your choice. As our kinetic energy, SD, and momentum data shows, the .308 Win is a very amazing cartridge and you can even hunt down the biggest game animals with the right choice of ammo. 

If you ask me which of these will I keep as a hunting round, the answer will always be .308 Win. 

Long Range Use

As the ballistics section already made it clear, the .308 Win was designed for and is extremely suitable for long range use. Whether it be ringing steel gongs at 500 yards plus or just some range fun. The 5.56 NATO is not very appropriate for long range applications and is more susceptible to yaw. 

Tactical Applications

This can be a tough one because both these rounds (7.62 NATO is very similar to .308 Win) are widely used around the world by armies and militias with an exceptional report card. Perhaps the .308 Win can be used with tactical rifles like the AR-10 or Sig 716 for versatile tactical usage, the 5.56 NATO is great for CQB and short range applications. 

Range Practice

Either of these rounds is great for range practice to hone your skills. The 5.56 NATO is more controllable with lesser recoil and is great for recoil sensitive shooters. Whereas the .308 Win is good to hone your recoil mitigation skills for when you’re out in the wild hunting. 

Home/Self Defense

It is sometimes a very debated topic on some forums about the .308 Win and 5.56 NATO being used for home defense. While the AR-15 is already preferred by many people for home defense which fires .223/5.56 rounds, the .308 Win can also be used for home defense or as a truck gun. 

However, in my opinion, I will not prefer either of these rounds for home defense if I’m living in an urban neighborhood. That is because these are rifle rounds and capable of going more than 300 yards carrying a significant amount of energy for penetration. Let’s just stick to our shotguns, handguns, pepper spray, and baseball clubs for home defense. Rather than dealing later with collateral damage. 

308 vs 556: Costs, Availability, & Compatibility

Apart from performance, it is also important to understand the availability and economics of cartridges. Afterall, you’re not being supplied by the military for an infinite amount of ammo. 

Cheap and Readily Available

One very interesting part of owning and using these cartridges are their insane availability and the scope for getting dirt-cheap deals. The .308 Win costs about a dollar per round on average and the 5.56 NATO comes for about 50 cents per round. Sure there are more expensive match-grade ammo options, but shooting either of these rounds on the range won’t burn a hole through your wallet. 

In fact, the 5.56 NATO is great for recreational shooting and mag dumps. Both these cartridges are widely and easily available across online and offline platforms. Plus, there are a ton of reloading supplies and ammo options for these. Even during the Covid-19 panic buying, these cartridges became a tad expensive but were still available. 

Versatile and Customizable

The fact that an AR-10 comes chambered for the .308 Win and an AR-15 comes chambered for the .223/5.56 opens up a ton of possibilities for rifle options and aftermarket upgrades. The .308 Win can be found in semi-auto and bolt action rifles, whereas the 5.56 NATO is mostly limited to semi-auto rifles due to its small size. 

Bottom Line

The .308 Winchester is the civilian version of the 7.62×51 mm aka the 7.62 NATO. It is a very popular hunting round and is also widely used by police snipers and even competitive shooters. It is undoubtedly a long range round with enough power to hunt down any game animal roaming this planet within a range of 300 yards. The best part is that is available for semi-auto actions.

On the other hand, the 5.56 NATO is the military version of the .223 Remington, the famous AR-15 chambering. It is a lightweight cartridge that fires light bullets and is best suited for hunting varmints and also CQB. The military uses it as the primary rifle cartridge, so tactical advantages are undoubtedly amazing. 

Each of these rounds is good for its appropriate purpose, and it is very likely an apple to oranges comparison.