5.56 A Superior Round?

[Dadtodabone]

keep in mind that basically every rifle has a wylde (hybrid) chamber nowadays.

Not sure why you would say that. Most ARs are 5.56 chambered which will fire both rounds. Some rifles are chambered for .223 wylde but they should say .223 wylde on the barrel. If it just says .223 then it is dangerous to shoot 5.56 in the rifle.

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Getting into the minutiae here, but I'm curious on a couple things with reference to this, specifically how it is dangerous to fire 5.56 in a .223 chamber. I'm aware I'm ranging into the pedantic here, but looking at my loading manuals, the external dimensions of both cartridges are, as we all know, identical. Therefore, it cannot be a difference in the cartridge itself (not yet getting into case wall thickness or pressure levels, more later).

I thought, "Well, maybe it's because the 5.56 has a longer throat and Overall Length, so it's an overpressure from hitting the rifling lands," except COL for the 5.56 is listed as .01" -shorter- than the .223, so that can't be it. (Info from Hornady manual, 5th edition)

So, overall velocities and pressures must be the culprit. The Hornady manual doesn't list data for identical bullets across the two cartridges, stopping at 60 grains for .223, and starting at 68 for 5.56. Unfortunately, it also fails to list pressures, so can't do a comparison there. Lee and Lyman both list pressure, but neither makes any distinction between the two. Probably the most complete manual I own, the Speer manual, mentions the 5.56 merely in passing as another name for the .223. No manual lists any pressure difference between the two, nor do they advise against firing either one in the other. In fact, Hornady lists loads for several of its bullets that are right up there, velocity-wise, with the above-mentioned 5.56 loads. The 5.56 is -slightly- hotter, but absent any actual pressure data to indicate otherwise, I don't see any real practical difference.

Given that barrels are proof-tested with deliberately grossly over-loaded rounds, a slight increase between 5.56 and .223 seems neglible. I could see how a steady diet of the hotter ammo, over a period of several years, could prematurely wear certain parts in the gun, but I fail to see how using 5.56 in a .223 is dangerous.

Thus, could you provide examples and references showing me I'm wrong? Not meaning any offense, but this brings back memories of people telling me not to fire .308 in my 7.62 Mauser, because it was dangerous, yet AFAIK, there was never a single example of a 7.62 Mauser blowing up due to the slightly hotter ammunition, only a "this might maybe could possibly stand a slight chance of happening, so it's dangerous to even think of it."

First, while I have never seen a catastrophic chamber failure, I have seen the most common over pressure problem with 5.56 in .a .223 chamber, primer loss. Having small pieces of metal drop into and interact with your trigger group may be an inconvenience on the range, that could have dire consequences when you are relying on the rifle for self defense purposes.
My second observation has more to do with my concern with the general manufacturing environment that we've experienced for the last 6 months, and that exhibited prior to and shortly after the 2008 election cycle.
I am reasonably certain that gunmakers who have a solid reputation for precision/quality processes didn't lay those aside to increase production, which is why their products are virtually nonexistent in the stocking dealer market.
I am equally certain that other gunmakers of lesser reputation have increased production to take advantage of recent market drivers to improve their sales/profitability. How were they able to do this? New hiring? Longer hours? Increased unit counts on tools and dies? New material suppliers? Reduced inspections?
While any one or two of these factors may not effect the safety of the firearm, the combination of a lesser quality firearm WITH overpressure from an equally rushed to production cartridge of either dimension gives me the willies.

[rotor]

5.56 is a hotter round, cases are heavier, primers are usually crimped, and before all the shortages it was easy to get those old 1000 round boxes of lake city miltary ammo. I believe it was even cheaper than the WM 223 100 round value packs. It was also easy to get tracer ammo for 5.56. If everything you do is at the range I would go with the cheapest. If your rifle is 5.56 it will shoot 223, but don't reverse that as kaboom is possible.

[The Annoyed Man]

Here's why you don't shoot 5.56 NATO in a .223 chamber:





Any questions?

[Dadtodabone]

Here's why you don't shoot 5.56 NATO in a .223 chamber:

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Any questions?

Oh my goodness! Not yours, I hope? Shooter okay?

[Beiruty]

squib rd?

[Abraham]

Is the shooter still alive?

Alive, but dreadfully injured?

Or, miraculously escaped this catastrophe unharmed?

I would also add that when the time comes, I'll make certain to buy a 5.56...

[Dadtodabone]

Is the shooter still alive?

Alive, but dreadfully injured?

Or, miraculously escaped this catastrophe unharmed?

I would also add that when the time comes, I'll make certain to buy a 5.56...

Check the barrel markings to make sure you're getting the 5.56, something like:
C MP 5.56 1/7
not:
C MP 223 1/12

[The Annoyed Man]

Here's why you don't shoot 5.56 NATO in a .223 chamber:

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Any questions?

Oh my goodness! Not yours, I hope? Shooter okay?

I searched Google images for "5.56 kaboom in .223 chamber" and these pictures were posted on another forum, both in the same post. I don't really know what happened to the shooter. http://www.rcgroups.com/forums/showthread.php?t=1845628, 3 or 4 posts down the page.

[JSThane]

Here's why you don't shoot 5.56 NATO in a .223 chamber:

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Any questions?

Oh my goodness! Not yours, I hope? Shooter okay?

I searched Google images for "5.56 kaboom in .223 chamber" and these pictures were posted on another forum, both in the same post. I don't really know what happened to the shooter. http://www.rcgroups.com/forums/showthread.php?t=1845628, 3 or 4 posts down the page.

I looked at the thread the picture was from, and the poster blamed it on a likely double-charge.

Followed the links therein to http://www.luckygunner.com/labs/5-56-vs-223" onclick="window.open(this.href);return false; . Apparently, the blown-up ARs are probably -not- the result of firing 5.56 in a .223 chamber, but squib rounds, double-charged, wrong powder, etc. In fact, according to his measurements, there can be a significant range of chamber sizes and differences in pressure curves in 5.56 chambers as well as .223, albeit .223 -tends- to have a tighter chamber, and 5.56 -tends- to higher pressure.
The popped primer falling into the trigger mechanism is mentioned, so whether that's an internet rumor or a documented anecdote, I don't know.

This is I got from his write-up, and the web-link wandering that followed:
A rifle suffering a catastrophic failure from firing 5.56 in a .223 chamber -could- happen, but is very unlikely.
A rifle suffering a catastrophic failure from firing improperly manufactured / improperly handloaded ammunition is more likely.
On average, 5.56 barrels have -slightly- larger, and therefore lower-pressure, chambers than .223 barrels.
A 5.56-chambered barrel will be -slightly- more tolerant of over-pressure situations, on average, and a .223-chambered barrel will be -slightly- more accurate, on average, -given- that both barrels come from a quality, reputable manufacturer, AND that the ammo is also of quality manufacture.
Due to high demand, spotty quality control, worn equipment, and a host of other issues, that -most- 5.56 chambers AND .223 chambers will exhibit ranges of actual dimensions and pressures, and these ranges will overlap. Therefore, an overpressure situation in one 5.56 chamber actually -could- be perfectly safe in another .223 chamber, because of these manufacturing differences.
On average, a .223 barrel will be -slightly- more accurate than a 5.56 barrel, given the same ammunition, barrel length, rifling twist, and manufacturer.
Most people will never know the difference.



For the record, this whole thing is academic to me; both of our ARs are marked 5.56/.223, so are rated to handle both, and are more accurate than I am. I was curious, though, and wondered if anyone else was able to find a specific instance of the "wrong ammo" causing damage. It looks to me and my admittedly incomplete "research" as though this is as much an internet tale as the 7.62/.308 dichotomy; in other words, it -could- cause catastrophic damage, but bad ammo or poor quality control, regardless of markings, is a bigger danger. However, using 5.56 in a .223 is NOT recommended, because of the slight, but present, possibility of a failure, so play it safe and get a 5.56 chamber.

TAM, many thanks for the links!