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View Full Version : FS- NEW DPMS 16" Bull Barrel Flat Top Upper-SOLD


reloadyour9
01-18-2010, 9:56 PM
SOLD

doc1buc
01-19-2010, 12:17 AM
Free Bump:
What is twist rate?
Do you take PayPal?
Is barrell marked 5.56 or .223?
Will you Ship?

FBO
01-19-2010, 12:34 AM
I thought 5.56 is .223, no? new to guns so trying to learn sorry :)

reloadyour9
01-19-2010, 12:47 AM
Twist is 1-9
marked 5.56
yes I'll take paypal as long as 3% charge is covered
yes I'll ship on buyers dime

5.56 and .223 are slightly different, however a 5.56 can fire both cartridges where as a .223 cannot

DENCO
01-19-2010, 6:45 AM
Twist is 1-9
marked 5.56
yes I'll take paypal as long as 3% charge is covered
yes I'll ship on buyers dime

5.56 and .223 are slightly different, however a 5.56 can fire both cartridges where as a .223 cannot


Thats confusing? I thought the difference was the bullet weight, and needed to be 1 in 9 twist to shoot the heavier round. The caliber is still .223 - no?

coop44
01-19-2010, 7:01 AM
Thats confusing? I thought the difference was the bullet weight, and needed to be 1 in 9 twist to shoot the heavier round. The caliber is still .223 - no?

It'll still shoot 223 556 whatever, buy it

ragenmoan
01-19-2010, 7:34 AM
The difference is significant.
From wikipedia....

While the 5.56 mm and .223 cartridges are very similar, they are not identical. Military cases are made from thicker brass than commercial cases, which reduces the powder capacity (an important consideration for handloaders), and the NATO specification allows a higher chamber pressure. Test barrels made for 5.56 mm NATO measure chamber pressure at the case mouth, as opposed to the SAAMI location. This difference accounts for upwards of 20,000+ psi difference in pressure measurements. That means that advertised pressure of 58,000 psi for 5.56 mm NATO, is around 78,000 psi tested in .223 Rem test barrels (SAAMI .223 Rem Proof MAP is 78,500 psi so every 5.56 mm round fired is a proof load, very dangerous). The 5.56 mm chambering, known as a NATO or mil-spec chambers, have a longer leade, which is the distance between the mouth of the cartridge and the point at which the rifling engages the bullet. The .223 chambering, known as the "SAAMI chamber", is allowed to have a shorter leade, and is only required to be proof tested to the lower SAAMI chamber pressure. To address these issues, various proprietary chambers exist, such as the Wylde chamber[2] or the Armalite chamber, which are designed to handle both 5.56 mm and .223 equally well.


These 5.56x45mm NATO cartridges are identical in appearance to .223 Remington. They are, however, not completely interchangeable.
Using commercial .223 cartridges in a 5.56-chambered rifle should work reliably, but generally will not be as accurate as when fired from a .223-chambered gun due to the excessive lead. [3] Using 5.56 mil-spec cartridges (such as the M855) in a .223-chambered rifle can lead to excessive wear and stress on the rifle and even be unsafe, and the SAAMI recommends against the practice.[4] Some commercial rifles marked as ".223 Remington" are in fact suited for 5.56 mm, such as many commercial AR-15 variants and the Ruger Mini-14[5], but the manufacturer should always be consulted to verify that this is acceptable before attempting it, and signs of excessive pressure (such as flattening or gas staining of the primers) should be looked for in the initial testing with 5.56 mm ammunition.

reloadyour9
01-19-2010, 4:30 PM
Thank god for Wikipedia!!!! BTT

reloadyour9
01-20-2010, 4:49 PM
bump

sirgiles
01-20-2010, 5:33 PM
http://www.6mmbr.com/223Rem.html

reloadyour9
01-21-2010, 5:07 PM
bump