What are the differences .223 vs 5.56?

[Bill92869]

Having been away form the sport for the past 20 years, I am just now getting back into it. As a shooter AND a reloader, I am curious about the apparent difference between a ".223" and a "5.56". I always thought they were two names for the same animal.

[GSequoia]

Rounds advertised / marked as 5.56 *should* be loaded hotter than rounds advertised / marked as .223.

See here: http://en.wikipedia.org/wiki/.223#.2...s_5.56_mm_NATO

[Bill92869]

Wow! I was not aware of this. So if I'm reloading for my Original Colt Ar (vintage 1970) and my Stag Arms OLL build (vintage 2007) , both of which are 5.56 chambered, should I be using only military brass or commercial brass listed as 5.56? And what about my old RCBS reloading dies, they're marked .223? Do I need to get 5.56 dies? Lastly, what little info I can find in reloading manuals (admittedly older ones) only show .223 or say for both .223 and 5.56 as if they were the same.

[ocabj]

Read the FAQ at http://www.ammo-oracle.com

[M1Shooter]

[Fjold]

[Bill92869]

Thanks M1 Shooter and Fjold. With your explanations I fully understand the differences. Based on that, would it be an accurate statement that .223 ammo is safe to shoot in a 5.56 chambered weapon, but that shooting 5.56 ammo (especially rounds with heavier/longer bullets) in a weapon with a .223 chamber could be dangerous? Would it also be accurate to say that accuracy of .223 ammo in a 5.56 chamber is somewhat diminished due to the "bullet jump" before engaging the rifling?

[M1Shooter]

Now you got it "grasshopper."

Good luck, good shooting, and Happy Thanksgiving.

[Bill92869]

Grasshopper? Does that mean I can leave the temple???

[Fjold]

Based on what was said above would you say that a rifle chambered in .223 is inherently more accurate than one chambered in 5.56 due to the longer throat and the fact that the bullets are the same dimension.

If the ammunition was loaded to SAAMI 223 specification it should be more accurate in a 223 chamber but less reliable in an autoloader due to the close tolerances of the chamber dimensions. The "match" chambering for autoloaders is the Wylde chamber.

[rix]

So, I'm assuming I can use .233 relaoding dies...? Also , can anyone show me where to find 5.56 load recipes?

[ocabj]

Based on what was said above would you say that a rifle chambered in .223 is inherently more accurate than one chambered in 5.56 due to the longer throat and the fact that the bullets are the same dimension.

Actually, 5.56 has a longer throat than SAAMI .223 Remington.

Here's an interesting read for those unfamiliar with .223 Remington, 5.56 NATO, and .223 Wylde.

http://www.zediker.com/articles/AR_chambers.pdf

[Bill92869]

Not having reloading data handy, can someone confirm this:

Is the overall loaded round length the same between .223 and 5.56? I'm guessing the 5.56 will be longer, which prompts my next question:

Is a heavier bullet (greater than the 55 grainers I have used in the past) needed or the reason for the longer OAL?

[-hanko]

Not having reloading data handy, can someone confirm this:

Is the overall loaded round length the same between .223 and 5.56? I'm guessing the 5.56 will be longer, which prompts my next question:

Is a heavier bullet (greater than the 55 grainers I have used in the past) needed or the reason for the longer OAL?

OAL for reloads should be indicated in your manual(s)...if it's not specified, use SAAMI maximum oal. For a bolt gun, I'd go 8-12 thou short of kissing the bore. For a semi-auto, use the oal in your reloading recipe(s).

Bullet weight does not control oal...military chambers are bigger to allow the gun to feed almost anything; difference between SAAMI and NATO is the chamber. The reloading forum on arfcom is worth checking every week or so.

-hanko

[bonjing]

so do the same rules apply to .308 vs 7.62?