5.56x45mm SDC

5.56mm SDC rounds compared to a single 7.62x51mm SDC round.

The **5.56x45mm SDC** is a rimless, bottlenecked intermediate cartridge developed for modern assault rifles, carbines and even marksman rifles. The Intermediate round features high velocity, moderately (but widely considered effective) powerful stopping power, with great accuracy and a relatively flat trajectory at longer distances. Heavily used by Sacrosanct Defense Coalition, serving as standard cartridge for their military forces; easily making ammunition readily available at the user's disposal.

Aforementioned above, It is a rimless, bottlenecked intermediate cartridge developed by Holt's Firearms Incorporated as an intermediate cartridge variant from the bigger 7.62x51mm SDC for smaller caliber rifles, and a solution to the flawed .223 Striker caliber, due to it's inaccuracy at long ranges. It is introduced into service in 1963 by the Nevians and remained in service until 2035.

## Description

The 5.56x45mm SDC weighs between 240-320 Grams due to its heavy load of CV6 gunpowder, that eliminates fouling and jamming on the used weapon. It is a cartridge that almost has a similar appearance like its Earth counterpart. The SS878 Striker cartridge is primarily notable for having a heavily reinforced Copper Jacket with a 9090 Titanium Alloy core/primer slightly protruding on the top, completely Lead Free, The muzzle velocity's standard rate of 3,000 Feet per second. Not to mention the longer the barrel, the more stable the flight path of the round so it will be heavily resistant against weather conditions. The base effective range of the round is 400 meters; so a MK4 carbine with a 14.5" barrel had five hundred meters, and a 20" inch full sized assault rifle such as the MK16A2 had 800 meters; a rifle with a barrel length longer than 20 inches (508mm), will not have increased range but accuracy and precision is furthermore improved.

Fragmentation, if and when it occurs, imparts much greater damage to human tissue than bullet dimensions and velocities would suggest. This fragmentation effect is highly dependent on velocity, and therefore barrel length: short-barreled carbines generate less muzzle velocity and therefore lose wounding effectiveness at much shorter ranges than longer-barreled rifles. It tends to over penetrate at human targtes, especially long barreled rifles; however they will *not* pass through a human target with ease at 450-600 meters, specifically if the target is wearing body armor that stopped the round, which was proven on the current version, the SS878 Striker cartridge.

Since fragmentation and Yawing are already impressive for such an intermediate cartridge, it is still dependent on barrel length, particularly muzzle velocity. So a 20 inch (508mm) rifled barrel (or longer) will produce the best ballistic performance (Accuracy, lethality, penetration, wind resistance, flatter trajectory and muzzle velocity) compared to shorter barrel lengths.

Due to its inhuman materials, the round is more capable of easily penetrating wood, brick, mild steel and other surfaces with ease. And Tree barks are virtually useless against it, as it can be penetrated with ease, regardless of their thickness.

### Variants

Since Rosearms Inc. introduced the intermediate caliber, it has been exposed to multiple ugprades and modifications at hand.

* **SS218**: Standard issue and lacks any identifiable markings, and the *titanium core* is concealed. It is noted for it's extreme fragmentation that causes massive damage; Making them less effective at surface penetration by at least 25%; For carbines, accuracy is reduced, while regular sized rifles need to fire semi automatic to deliver precise shots at 500 to 600 meters.

* **SS878 Striker**: Reduced fragmentation, Standard Issue FMJ round; intended for law enforcement and military personnel, Recognizable for the protruding 9090 Titanium Alloy core, while copper covered less of the core; lead free. It is typically effective against variety of targets, objects, furniture and surfaces, Although it had a slightly lower muzzle velocity than its predecessor, it had better long-range performance due to higher sectional density and a superior drag coefficient, and significantly improved lethality. It is widely considered to be weaker than the 218; But this was incorrect considering it delivers a better stopping power due to a reinforced bullet.

* **SS268-Scorcher**: Special ammunition loaded with phosphorus coated in the primer of the cartridge. Lesser penetration level due to the bullet softened after striking the specific target with the flammable content.

* **XREP Electro**: Defined as *eXtended Range Electronic Projectile*; The XREP looks like a high-tech cartridge. That's not by accident; Rubicon Corporation designed the XREP so that military or law enforcement officers could fire one from a standard **5.56x45mm SDC** firearm. But instead of firing pellets or a slug, they fire a miniature, self-contained Taser device capable of delivering the same *neuromuscular incapacitation* effect as a handheld Taser pistol.

* **SS987-Bulwark**: Classed as an *Enhanced Performance Round* by Rubicon, Improved ballistics for long range and typically chosen for Marksman rifles; However it can be also used on typical 5.56mm rifles and carbines.

* **SS888-Brutalizer**: Hollow pointed ammunition, with a brittle chromium outer sheath encasing the 9090 Titanium Alloy core projectile; It causes extreme wounds by the fragmentation of the chromium shell against the struck target. It has been banned from due to the Panamoan Weapons Law of 1986 for sheer brutality.

* **SS785 Bloodsucker**: Manufactured by Albino Ordinance, this variant is essentially similar to the Brutalizer, but it "absorbs" the blood of the victim, making a wounded target suffer from extensive blood loss, but using it on non-living objects simply behaves like the Striker variant, and was banned for sale by the ICPF, and nicknamed the "Vampire's Fang".

## Compatible Weapons

### Assault Rifles and Carbines

* AR552C
* AR805
* M556
* AC556
* ACR 5.56
* MK16
* MK16A1
* MK16A2
* MK16A3
* MK16A4
* MK16A5
* MK4A1
* MK5 Maverick
* XMK4

### Light Machine Guns

* MG556 Grinder
* SAW-74

## Trivia

### General

* The Round has a tendency to yaw while going straight to a target, so longer barreled Assault rifles using the 5.56x45mm SDC will tend to create intense internal injuries while zipping through the target's body.
* It tends to over penetrate against soft surfaces and living targets, which is very true to long barreled 5.56x45mm SDC Assault rifles.
* It is called the "meat axe" by Panamoan soldiers, due to it's effectiveness.
* The success of this cartridge forced the Evalkan Empire to create a knockoff design, which s the *5.45x39mm NEC*, which is based from the 5.45x39mm Orzakyen cartridge from Boreas.