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View Full Version : .223 vs. 5.56 question


MonsterMan
08-09-2006, 5:43 PM
I read this online and it made me wonder.

"The .223 Remington can be safely fired in a 5.56 mm chamber, but the reverse is an unsafe combination that causes extreme pressures and could damage or destroy the rifle."

Any truth to this? I have fired 5.56 in my Mini-14 and nothing happened. I always thought it didn't matter, they were basically the same, aside from minor differences.

MM

M. Sage
08-09-2006, 5:51 PM
http://www.ammo-oracle.com/body.htm#diff

Dimensionally, 5.56 and .223 ammo are identical, though military 5.56 ammo is typically loaded to higher pressures and velocities than commercial ammo and may, in guns with extremely tight "match" .223 chambers, be unsafe to fire.

Read that, it'll tell you.

You can also search on the SAAMI site, the link at Ammo Oracle is dead.

bu-bye
08-09-2006, 5:54 PM
I don't have a degree in physics and I have not done testing of my own with many rifles but I can say that my DPMS bull barrel is chambered in 223 yet I only shoot 5.56 XM193, M855, or my personal reloads using Lake City brass for the past 4 years and have not had any problems. I also have friends that also shoot 5.56 out of a barrel marked as 223. I'm no pro and don't suggest anything but that is what I shoot and what I will continue to shoot.

Kestryll
08-09-2006, 6:03 PM
The two rounds are close enough to interchange in some instances but there are differences.
http://www.ammo-oracle.com/images/556cham.gif

The Mini-14 is chambered to take the 5.56 from what I've read.

VeryCoolCat
08-09-2006, 6:08 PM
I think the mini-14 was designed for "hotter" rounds as I always hear bad about running wolf through the thing. Same for the mini-30 and wolf 7.62x39

PIRATE14
08-09-2006, 7:15 PM
I read this online and it made me wonder.

"The .223 Remington can be safely fired in a 5.56 mm chamber, but the reverse is an unsafe combination that causes extreme pressures and could damage or destroy the rifle."

Any truth to this? I have fired 5.56 in my Mini-14 and nothing happened. I always thought it didn't matter, they were basically the same, aside from minor differences.

MM

Well, I've never heard of a KABOOM but some barrels chambered for 223 won't work with 5.56.....SOME Barrels......

M. Sage
08-09-2006, 8:38 PM
Well, I've never heard of a KABOOM but some barrels chambered for 223 won't work with 5.56.....SOME Barrels......

Just read the AR15.com Ammo Oracle. It MAY be unsafe in some barrels. According to SAAMI, anyway.

NeoWeird
08-09-2006, 9:13 PM
Keep in mind also that the casing, while near exact, is still dimensionally different. This is usually not a problem on new, high quality, or properly maintained rifles however on lower quaity, cheap, or worn rifles it can cause problems. For example, the 5.56 is .002 longer than the .223. This normally is acceptable, but if you have a rifle reaching the limits of it's headspace, the .223 may be too short and might allow gases rearward and could cause damage to you or the rifle. I'm not saying don't do it, just be careful, and as always have someone in the know check it out before you shoot it if you are unsure (doesn't need to be a gunsmith, a knowledgable friend or shooting buddy could do it).

Ryan HBC
08-09-2006, 9:33 PM
The way I understand it, it all has to do with the pressures. .223 chamers are tighter than 5.56 chambers. This makes .223 chambers more accurate, but also makes them unsafe for the higher pressures that 5.56 rounds are loaded to.

xenophobe
08-09-2006, 9:56 PM
The Mini-14 is chambered to take the 5.56 from what I've read.

From my understanding, you're correct. I've read somewhere that the Mini-14, although is labeled .223, is actually chambered for 5.56x45mm.

grammaton76
08-09-2006, 10:15 PM
I've heard the SU-16 is also set up for 5.56mm, as opposed to 223

Super_tactical
08-09-2006, 11:29 PM
I've heard the SU-16 is also set up for 5.56mm, as opposed to 223
My SU16 says .223 on the side. :confused:

I called Keltec and the lady didn't know. I didn't feel like probing any deeper at the time.

grammaton76
08-10-2006, 1:09 AM
My SU16 says .223 on the side. :confused:

I called Keltec and the lady didn't know. I didn't feel like probing any deeper at the time.

Which model do you have? I'd specifically heard it about the CA, which is mine...

Super_tactical
08-10-2006, 2:16 AM
Which model do you have? I'd specifically heard it about the CA, which is mine...
I think I have the Su-16B... not the CA, no threaded barrel or AR front sight/block

C.G.
08-10-2006, 7:12 AM
My SU16 says .223 on the side. :confused:

I called Keltec and the lady didn't know. I didn't feel like probing any deeper at the time.

My former SU16A also used to say .223. Keltec said I can feed it .223 or 5.56, but advised against aluminum or steel casings.

bu-bye
08-10-2006, 9:48 AM
Well my SU-16CA only eats 5.56 and its still here so should be ok.

MonsterMan
08-10-2006, 10:08 AM
Thanks everyone.

MM

norm113
05-20-2010, 8:08 PM
Well the Mini-14 is a odd animal. The owners manual for the Mini-14 andMini-14 ranch say that both .223 and 5.56 can be used in the gun. But the Target model will only fire .223.

Norm

xxINKxx
05-20-2010, 8:21 PM
And we have a record !

Ya, Ive noticed today in general, there has been some serious old thread bumps going on.

Josh3239
05-20-2010, 8:40 PM
Wow, a thread that has been revived from 4 years ago. Great :rolleyes: