5.56mm vs. .223 cal.
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CAUTION: I have seen numerous forums and discussions regarding these two cartridges and the debate rages on apparently. First and foremost, there IS no debate here, the cartridges ARE different, this is a fact not a point of debate, end of story. However, if you want more reason, continue reading.
Very few expressing concern for the dangers... It is one thing to gamble with your own well being, however, it's quite another to gamble with the well being of those around you. Where the manufacturers of barrels, gauges, reamers and cartridges strongly suggest against creating this risky situation. You wouldn't consider placing a 7.62mm cartridge in your .223 chamber. Why not? Simple.. Because it doesn't FIT! Shouldn't we be applying the same rationale here? We shouldn't place a 5.56mm cartridge in a .223 chamber. Doing so violates the first law of handling weapons, SAFETY! Gun accidents always happen when someone carelessly forgets simple gun safety and to knowingly endanger yourself and those around you, is simply ludicrous, irresponsible and criminal in the event someone gets injured.
Similar Cartridges If you EVER plan on shooting NATO 5.56mm ammunition in your AR, then DO NOT buy a .223 chambered barrel. Also consider, that the NATO 5.56mm cartridge is only the most common and widely available AR15 cartridge anywhere so why would you even consider purchasing a .223 chambered barrel. This is particularly true if the barrel is chromed as that reduces the clearances even more.
Here's the problem. SAAMI proscribes (denounces as dangerous or harmful) the use of 5.56mm military ammunition in rifles chambered for .223 Remington. Remington was the original manufacturer of the ".222 Special" ammunition designed by Eugene Stoner for the AR-15. This cartridge design was standardized as 5.56mm (5.56x45mm) by the US Army. Concurrently, Remington added the cartridge to their product line as the ".223 Remington." However, there are small, subtle differences between the two. If you hold the two cartridges side by side you won't be able to discern the differences, as they are several thousandths of an inch here and there. Army 5.56mm ammunition has more tolerance in the case neck diameter than the civilian SAAMI .223 Remington chamber drawing. It is possible to fire .223 Remington cartridges in 5.56mm chambers. It is also possible to fire 5.56mm cartridges in .223 Remington chambers, BUT the tighter civilian chamber spec MAY cause certain types or lots of 5.56mm ammunition to fit too tightly for proper function and could cause severe damage or injury. The .223 Remington is rated for a maximum of 50,000 CUP while the 5.56mm is rated for 60,000 CUP. That extra 10,000 CUP is likely sufficient to cause a failure in a chamber that's only rated for the "sporting" .223 Remington. The .223 Remington and the 5.56mm NATO, when checked with a chamber GOOD reamer, also have discernable differences in the areas of freebore diameter, freebore length Leade and angle of the throat.
SAAMI
223 and 5.56mm Reamer Dimensions
Leade
Leade is the distance the projectile of a chambered round must travel upon ignition before it enters the bore of a barrel. It is measured in thousandths of an inch, and is a datum of considerable interest to benchrest shooters. |