Cannonball888
Member
What are the disadvatages, if any, of firing .223 in a rifle chambered for 5.56 NATO and vice versa?
Not unless you want to shoot it loose, or like using broken shell extractors.Stringer said:Don't fire 5.56x45 ammo in a .223 rifle. The opposite is OK though.
Gun lover said:What about shooting 5.56 out of a Mini 14?
The Ruger Mini-14 Ranch Rifles are chambered for the .223 Remington (5.56mm) cartridge. The Ranch Rifle is designed to use either standardiz (sic) U.S. military or factory loaded sporting .223 (5.56mm) cartridges manufactured in accordance with U.S. industry practice.
I have yet, however, to find a major rifle manufacturer who says "don't use 5.56mm in our .223 rifles!!!
http://www.6mmbr.com/223Rem.html
The .223 Remington is the most widely-used centerfire rifle cartridge in the developed world. In its 5.56x45 military form, it is the primary issue ammunition for the U.S. Military and NATO forces. It is a popular sporting cartridge, and probably the most commonly used centerfire varmint cartridge. In our Readers' Poll, the .223 Rem (both standard and improved) ranked first among preferred varmint rounds. The .223 Rem is efficient and versatile. It can sling 40-grainers past 3650 fps, and deliver 90gr VLDs accurately at 1000 yards. Its parent case, the .222 Remington, was once a mainstay of benchrest competition. Today, with custom match bullets, the .223 Remington can still deliver impressive accuracy, shooting well under quarter-MOA in a good rifle.
.223 Remington Cartridge History
The .223 Rem was derived from the .222 Remington, a round popular with benchrest and varmint shooters in the 1950s. The U.S. Army was looking for a new, high-speed small-caliber round to replace the .308 Winchester (7.62x51). To increase velocity with a 55gr bullet, the U.S. Military bumped the .222 Rem's case capacity by pushing forward the shoulder and shortening the neck. This military modification of the .222 Remington was originally called the .222 Special but was later renamed the .223 Remington. In military metric nomenclature, the round is called the 5.56x45. For the full history of the 5.56x45 cartridge, read the 5.56x45 Timeline, by Daniel Watters.
223 Remington vs. 5.56x45--Chambering and Throat Considerations
Is the .223 Remington the same as the 5.56x45? The answer is yes and no. There ARE differences between the .223 Remington as shot in civilian rifles and the 5.56x45 in military use. While the external cartridge dimensions are essentially the same, the .223 Remington is built to SAAMI specs, rated to 50,000 CUP max pressure, and normally has a shorter throat. The 5.56x45 is built to NATO specs, rated to 60,000 CUP max pressure, and has a longer throat, optimized to shoot long bullets. That said, there are various .223 Remington match chambers, including the Wylde chamber, that feature longer throats. Military 5.56x45 brass often, but not always, has thicker internal construction, and slightly less capacity than commercial .223 Rem brass.
Should you be worried about shooting 5.56x45 milspec ammo in a .223 Remington?
The answer really depends on your chamber. 5.56 x45 ammo is intended for chambers with longer throats. If you shoot hot 5.56x45 ammo in short-throated SAAMI-spec chambers you can encounter pressure issues. The new long-throated 'Wylde' chamber allows safe use of military ammo. Wylde chambers are quite common in Rock River guns. Other manufacturers, such as Fulton Armory, offer modified "match chambers" with extended throats that allow safe use of 5.56x45 ammo in .223 Remington rifles. For a complete discussion of the .223 Rem vs. 5.56x45 question, read this Tech Notice from Winchester, and this GunZone Commentary by Dean Speir. Without belaboring the point, we'll repeat the official SAAMI position: "Chambers for military rifles have a different throat configuration than chambers for sporting firearms which, together with the full metal jacket of the military projectile, may account for the higher pressures which result when military ammunition is fired in a sporting chamber. SAAMI recommends that a firearm be fired only with the cartridge for which it is specifically chambered by the manufacturer."