.223 Remington vs 5.56 NATO: Know the Difference Before You Fire
.223 Remington vs 5.56 NATO: Know the Difference Before You Fire
History of 5.56 NATO:
The 5.56×45mm NATO (often called “five-five-six”) is a type of bullet used in military rifles. It was created in the late 1970s in Belgium by a company called FN Herstal. This bullet family includes types called SS109, L110, and SS111.
On October 28, 1980, NATO (a group of countries that work together on defence) officially chose it as one of their standard bullets for rifles. Many other countries outside NATO also use it.
The 5.56 NATO bullet is based on an older bullet called the .223 Remington, which was made in the early 1960s by Remington Arms. These two bullets look very similar, but the 5.56 NATO fires a slightly bigger bullet and is built for military use.
History of .223 Remington:
The .223 Remington (often said as “two-two-three”) is a type of bullet. It has a rimless, bottlenecked shape and uses centrefire ignition, which is common in rifle bullets.
It was designed in 1957 by Remington Arms and Fairchild Industries for the U.S. Army. The goal was to make a small bullet that could travel very fast.
This bullet fires a .2245 inch (5.70 mm) sized projectile. Today, the .223 Remington is very popular and is used in many types of semi-automatic and manual (bolt-action) rifles by hunters, sport shooters, and gun owners around the world.
Difference between the projectiles and case length 5.56 vs .223
The projectile (bullet tip) of the 5.56mm appears slightly longer than the .223.
The case length is nearly the same (both use 45mm cases), but the bullet on the 5.56mm is seated slightly deeper or has a longer ogive (bullet shape), which adds to overall length.
Overall Cartridge Length ~2.26 in (57.4 mm) ~2.26 in (57.4 mm) (same, per spec)
Bullet Length Varies, ~0.75–0.9 in (depending on weight) Can be longer, especially M855 (62 gr) or Mk 262 (77 gr)
Bullet Seating Usually shorter bullets seated shallower Longer bullets seated deeper to fit same OAL.
Main difference between the 5.56 vs .223 Remington:
1.Pressure:
The 5.56×45mm NATO operates at a higher pressure (about 58,000 to 62,000 psi), while the .223 Remington runs at a lower pressure (around 55,000 psi).
2. Chamber:
The 5.56 has a larger chamber throat with a longer free bore, whereas the .223 has a tighter chamber and a shorter throat.
3. Bullet Seating:
5.56 NATO usually uses heavier or longer bullets that are seated deeper in the case, while .223 Remington typically uses lighter bullets that are seated more shallow.
4. Case Wall Thickness:
5.56 brass has slightly thicker case walls, making it stronger for military use. .223 brass is thinner and optimized for lower-pressure loads.
5. Accuracy:
5.56 may be less accurate in civilian rifles due to its military design, while .223 is often more accurate in precision shooting setups.
6. Interchangeability:
You can fire .223 in a 5.56 rifle safely, but firing 5.56 in a .223 rifle can be dangerous due to higher pressure.
7. Use:
5.56 is built for military-grade rifles, including full-auto weapons, while .223 is made for civilian use, such as hunting and sport shooting.
8. Twist Rate:
5.56 rifles often use faster twist rates like 1:7 or 1:9 to stabilize heavier bullets. .223 rifles may have slower twist rates like 1:9 or 1:12, suited for lighter bullets.
Leade and free bore in 5.56 and .233 Remington:
Freebore:
The freebore is the smooth, unrifled part of the barrel just ahead of the chamber, before the rifling (grooves) begins.
It allows the bullet to travel a short distance before engaging the rifling. The free bore is larger diameter than groove diameter.
Leade:
The leade is the tapered or angled transition from the free bore into the rifling.
It’s what guides the bullet into the rifling smoothly.
Sometimes, “leade” is used interchangeably with free bore, but technically, leade = free bore + angle.
Free bore:
The 5.56 NATO has a longer free bore, about 0.056 inches, while the .223 Remington has a shorter free bore, around 0.025 inches.
Leade Angle:
The leade in 5.56 NATO has a shallower angle and a longer transition into the rifling. In contrast, .223 Remington has a steeper leade angle with a shorter transition.
Effect:
The longer free bore and shallow leade in 5.56 allows more space before the bullet hits the rifling, which helps handle higher pressure safely.
The shorter free bore and steeper leade in .223 means the bullet contacts the rifling faster, making it more precise, but it has less pressure tolerance.
5.56 NATO chambers have a longer free bore/leade, which lets the bullet “jump” a bit before hitting the rifling.
This reduces pressure spikes, so it can safely shoot hotter loads (military rounds).
.223 Remington chambers have shorter free bore/leade, so the bullet engages the rifling almost immediately.
This improves accuracy, but firing a 5.56 round in a .223 chamber can create dangerous pressure.
The longer leade in 5.56 = safer with hot ammo, less accurate.
The shorter leade in .223 = more accurate, but can’t handle 5.56 pressure safely.
Advantages of Long Leade (like in 5.56 NATO)
Handles higher pressure: More space before rifling reduces pressure spikes
Better for military/hot loads: Prevents overpressure in rapid fire or full-auto use
Supports longer/heavier bullets: Can seat bullets deeper while staying within safe OAL
More reliable feeding: Bullet jump can reduce chances of jamming in combat environments due to loose tolerance
Safer in mixed-ammo use: Reduces risk when using different brands or hotter loads
Advantages of Short Leade (like in .223 Remington)
Improved accuracy Bullet: contacts rifling quickly, reducing bullet “jump”
Better for precision shooting: Ideal for target shooting, bench rest, and varmint hunting
Tighter chamber fit: Enhances consistency and bullet alignment
Lower recoil impulse: Faster engagement with rifling gives smoother shooting in some setups.
Purpose of Free bore:
Free bore is the smooth section of the barrel just in front of the cartridge.
Give the bullet space to move forward before touching the rifling.
Reduce pressure spikes by allowing the bullet to start moving more easily.
Improve safety when using higher-pressure or longer bullets (like military ammo).
Purpose of Leade:
Leade is the sloped part that connects the free bore to the rifling.
Guide the bullet smoothly into the rifling grooves.
Reduce stress on the bullet as it enters the rifling.
Help with accuracy by making sure the bullet enters straight and evenly.
Transitions in a Rifle Barrel (Bullet’s Path)
When the bullet is fired, it passes through three main areas inside the barrel:
Chamber to Free bore:
Transition: From the cartridge case to an unrifled smooth section.
Purpose: Allows the bullet to start moving forward without resistance.
Free bore to Leade
Transition: From smooth bore to a sloped entry.
Purpose: Gently guides the bullet toward the rifling to prevent damage and high pressure.
Leade → Rifling (Lands & Grooves)
Transition: From the sloped leade into full engagement with spiral grooves.
Purpose: The rifling grabs and spins the bullet to keep it stable and accurate in flight.
Comments
Post a Comment