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Posted on 10/29/2016 5:17:13 PM PDT by MtnClimber
Is firing a 5.56 NATO cartridge in your .223 Remington chambered AR15 dangerous? Or do Internet forum-ninjas and ammunition companies selling you commercial ammo instead of surplus overstate the dangers? Believe it or not, a real danger exists, and some gun owners who think they are doing the right thing may not be safe.
The Cartridges
The .223 Remington and 5.56×45 NATO cartridges are very similar, and externally appear the same. But there are some differences that lie beneath the surface.
The 5.56 case has thicker walls to handle higher pressures, meaning the interior volume of the case is smaller than that of a .223. This will alter the loading data used when reloading 5.56 brass to .223 specs.
Some 5.56 loads have a slightly longer overall length than commercial .223 loads.
The Chambers
The significant difference between the .223 Rem and 5.56 NATO lies in the rifles, rather than the cartridges themselves. Both the .223 and 5.56 rounds will chamber in rifles designed for either cartridge, but the critical component, leade, will be different in each rifle.
The leade is the area of the barrel in front of the chamber prior to where the rifling begins. This is where the loaded bullet is located when a cartridge is chambered. The leade is frequently called the “throat.”
On a .223 Remington spec rifle, the leade will be 0.085”. This is the standard described by the Sporting Arms and Ammunition Manufacturers’ Institute, Inc. (SAAMI). The leade in a 5.56 NATO spec rifle is 0.162”, or almost double the leade of the .223 rifle.
(Excerpt) Read more at bearingarms.com ...
I have heard of possible issues for years, but never an explanation.
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Dono, but if you get touched in the forehead with a .17 your future is a mess.
My newly purchased M-4 COLT has 5.56MM on the box, and the serial number. The same COLT rifle has .223 stamped on the rifle and the same serial number.
I have fired BOTH cartridges in a RUGER Mini-14 and other rifles with no problems.
I specifically bought a 5.56 to avoid the potential issues of buying .223 and using both ammo. So far I have strictly used 5.56 ammo in my Armalite Eagle-15.
With reloads I have seen signs of excessive pressure with loads that should be well below mazimum and now that I think of it it was military 5.56 brass.
Me too.
How about the leade?
Do research on the case dimensions. The geometry is different.
Wrong. Slightly higher chamber pressure for 5.56 vs .223 ammo. Results in about 150-200 fps difference. Not a huge difference but some and specifications behind that nomenclature.
Wylde about the potential ...... :o)
The case thickness and bullet seating dimensions are explained in the article. If you don’t reload then it may not make sense.
Yes, the thicker case for the 5.56 means pressure will be higher than a similar charge in .223. If you reload a max .223 charge in a 5.56 the pressure will high enough that you may get a case rupture.
That’s cool;) I only buy 5.56mm for target practice, but for personal defense I have 30-round mag’s (27 rounds) filled with .223 hollow points.
When reloading most sort out the military brass and the Commercial brass for the same capacity reason. Some go as far to weigh the brass for consistent loads.
The Armalite Eagle-15 I picked up last June is chambered in .223 Wylde. That's what sold me on it.
The Mini 14 is chambered for 5.56 which means you can use .223 also.If it was chambered in. 223 it would be a no bo to fire a 5.56 in it.
If the military brass has less internal capacity, it will take less of a given powder to reach a specific pressure than commercial .223. Chamber specs vary a bit between 5.56 and .223, and even the Wylde chamber. The cartridges, loaded to their respective pressures are interchangeable, the minute differences in chamber specs for reliability.
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