What is the best barrel length for 5.56 NATO?

For most loads, 5.56 NATO and . 223 Rem do best with a 16″ barrel and 1:8 twist rate. For . 308 and 7.62 NATO, a 20″ barrel and 1:12 twist rate works best for all loads.

What is the effective range of a 5.56 NATO round?

As previous studies concluded, a truly lethal maximum effective range for an M885, 5.56 mm NATO projectile is about 200 to 250 meters (218- 273 yards).

Is 556 or 545 better?

Originally Answered: Which is better, 5.45×39 or 5.56×45? The 5.45 is overall superior. It has advantage in accuracy because the case has less length to width ratio which means the propellant burns faster and more uniformly. The 5.45x39mm case is shorter and slightly more tapered for more reliable extraction.

What is the muzzle velocity of a 556 NATO?

922 m/s
5.56mm NATO versus 7.62mm NATO

Cartridge	Model	Velocity
5.56mm NATO	M855 5.56mm (5.56 × 45 mm) Ammunition	922 m/s (3,025 ft/s)
7.62mm NATO

What is the best twist rate for an AR-15 barrel?

The 1:9 barrel is best for stabilizing lighter and mid-weight bullets between 45 and 77 grains. The 1:8 twist barrel is the most versatile of the bunch, the perfect option for16-inch carbine AR-15 (the most common configuration on the market.)

How long should my AR barrel be?

16″
It should be kept in mind that legally, the shortest barrel you can get for an AR is 16″. You might be able to get away with a 14.5″ barrel if you pin a muzzle device on it to make the barrel 16″. Moving forward, the 16″ is perfect for any use, extremely reliable and most importantly, it is very accurate.

What does 5R rifling mean?

Definitions. 5R is a 5-groove rifling pattern with sloped or angled sides to the lands. All rifling has a certain amount of angle to the sides of the lands as a natural effect of the rifling process. The sides of the grooves are parallel, but the sides of the lands are not and the 5R carries this to an extreme.

What twist rate does the military use?

For those who are curious, Guns&Ammo notes that the military uses the 1:7 twist rate. So, why do you want a faster twist rate or a slower twist rate? The answer is simple: bullet weight. There are a wide variety of bullet weights available, anywhere between 30 and 80 grains, in the extremes of the 5.56 mm NATO/.

What is the best AR length?

20″ barrels provide the most consistent performance across the widest variety of loadings. There are plenty of modern specialized loads “optimized” for use in a 16″ barrel, but the 20″ length will still do things better. Aside from the benefits of velocity, the long 20″ barrel gives a balance benefit to marksmen.

What is the average velocity loss per inch of barrel length?

Utilizing the data from the 16.5″ barrel, average velocity loss per inch of barrel length was 22.5 ft/sec for the UMC 223 55-grain cartridge, 25.7 ft/sec for the Federal M-193 cartridge, 30.3 ft/sec for the Winchester M855 cartridge, and 22.8 ft/sec for the Black Hills 68-grain heavy match cartridge.

Why did the AR-15 barrel get shortened to 8 inches?

In this photo, the barrel has been shortened to eight inches. There has been a cultural shift from the 20-inch barrel length in the AR-15/M16 weapon systems chambered for the 5.56×45 NATO cartridge to progressively shorter barrels for the purpose of producing an increasingly more compact assault/entry weapon without resorting to a bull-pup design.

What is the muzzle velocity of a M855 bullet?

M855 bullets traveling below 2,500 fps when impacting a target will not produce a lethal wound channel. There have been a number of studies demonstrating the barrel external temperature gradient as a function of barrel length in addition to numerous studies of muzzle velocity as a function of length.

What is the velocity of the 223 55 grain cartridge?

It should be noted that the 17″ barrel length provided the slowest velocities in for the UMC 223 55 grain cartridge, Federal M-193 and Winchester M855 with velocity reductions of 260 ft/sec, 280 ft/sec and 308 ft/sec with each cartridge respectively.