For those who are more experienced with these particular calibers... is there a significant difference or are they considered essentially the same? Thanks in advance.
.223 Remington/5.56 mm difference
- Thread starter Beck_Hickok
- Start date
Thank you for the reply.
XTR
F-TR obssessed shooting junkie
http://forum.accurateshooter.com/threads/which-223-reamer.3922726/
the difference really exists only on the interwebz
http://ar15barrels.com/data/223-556.pdf
the difference really exists only on the interwebz
http://ar15barrels.com/data/223-556.pdf
And most of the load data seems to be for the .223. I run as long a cartridge that will fit in my AR mags which happens to be 2.300"
This is a picture I found online that helps explain the differences in the chambers.
As everyone else has said, it's in the free-run of the throat before the bullet contacts the rifling. The military wanted a small round with a big punch. To do this, while still staying within the pressure limits for the M-16, they cheated. They allowed the bullet an unusual free jump distance into the lands. This had the same internal ballistic effect as increasing the case volume. When Remington introduced the .223, they speced a more conventional throating.
Lone Hunter
Silver $$ Contributor
Here is articles and info on the 5.56/.223. There's a lot of info on there. Also, scroll down the page and you will see Sierra loading data for Bolt gun loads and data for AR's. Hornady also provides free data as most manufacturers do.
https://www.accurateshooter.com/cartridge-guides/223rem/
Yes. But what kinda bolt gun has a 5.56x45 chamber ???
You can't use 5.56 data for a 223 bolt gun because the 5.56 chambers have looser and longer freebore and usually are loaded a tiny bit hotter than 223rem.
5.56x45 and 223rem brass is the same, except military 5.56 NATO loaded ammo has a crimp on the primer pocket that needs swagging before reloading.
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Main differences are...
5.56x45 has wider freebore diameter than 223rem
5.56x45 has longer freebore than 223rem.
5.56x45 chamber has a little bit more generous headspace than 223rem.
5.56x45 can be (and often is ) loaded to higher pressures because of the longer and wider freebore.
If you take a 5.56 NATO loaded round and fire it in a 5.56 NATO chamber, the pressure will be around 55,000 PSI.
BUT... if you take that same exact round and fire it in a 223 Rem. chamber, the pressure can rise above 63,000 psi because of the chamber differences.
5.56x45 has wider freebore diameter than 223rem
5.56x45 has longer freebore than 223rem.
5.56x45 chamber has a little bit more generous headspace than 223rem.
5.56x45 can be (and often is ) loaded to higher pressures because of the longer and wider freebore.
If you take a 5.56 NATO loaded round and fire it in a 5.56 NATO chamber, the pressure will be around 55,000 PSI.
BUT... if you take that same exact round and fire it in a 223 Rem. chamber, the pressure can rise above 63,000 psi because of the chamber differences.
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The testing methodology between SAAMI and NATO/CIP is waaay different, and the NATO/CIP standard allows higher mean pressure. For proof of this refer to the Western Powders load guide. They provide a std 223 load guide using SAAMI methodolgy, plus a CIP/NATO section using CIP methodology, and a heavy bullet custom long throat section. This reveals all.
Mossberg makes bolt rifles in 5.56
https://www.cheaperthandirt.com/cat...er=5.56+NATO&pp=30&sortby=ourPicksAscend&cx=0
Unfortunately it has a 1/9 twist barrel that leaves me perplexed as to why they'd offer a long throat chamber capable of using 80 and 90 grain bullets but does not have the twist to support anything heavier/longer than a 77SMK that'll fit a std 223Rem?
What am I missing here?
I don't think you are missing a thing .I was simply answering a question posted earlier in the thread .
All I know is I have fired thousands of rounds of military 5.56 out of various Rem .223s over the years with no issues. Pulled the bullets, seated a good bullet over existing powder normally good for .5 groups. Won a lot of offhand matches with this combo. Sent a lot of groundhogs to the big clover field in the sky with them also.
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