SAF ammo: 5.56 or .223?
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So far all the 5.56 SAF ammo i see stamps 5.56 at the endcaps.
5.56mm is a military measurement.
.223 is civilian.
you can put a .223 cartridge into 5.56mm. but not the other way round.
5.56mm is not equal to .223. So is 7.62 not equal to .308.
dimensions wise .223 REM = 5.56 x 45 mm NATO. But they are not the same bullet.
Just like 7.62 x 55 mm NATO in dimension = to .308 WIN.
A civilian M-16 (or any AR-15 family of rifles) are marked .223 REM. you can chamber a 5.56mm NATO, but it is not advisable to fire from it. But you can chamber and fire a .223 REM in a military M-16.
THis is because the chamber is built to withstand the military load. -
difference in gunpowder grade, bullet head density etc. right?Originally posted by Ponders:So far all the 5.56 SAF ammo i see stamps 5.56 at the endcaps.
5.56mm is a military measurement.
.223 is civilian.
you can put a .223 cartridge into 5.56mm. but not the other way round.
5.56mm is not equal to .223. So is 7.62 not equal to .308.
dimensions wise .223 REM = 5.56 x 45 mm NATO. But they are not the same bullet.
Just like 7.62 x 55 mm NATO in dimension = to .308 WIN.
A civilian M-16 (or any AR-15 family of rifles) are marked .223 REM. you can chamber a 5.56mm NATO, but it is not advisable to fire from it. But you can chamber and fire a .223 REM in a military M-16.
THis is because the chamber is built to withstand the military load. -
Any articles on the web to substantiate this?Originally posted by Ponders:A civilian M-16 (or any AR-15 family of rifles) are marked .223 REM. you can chamber a 5.56mm NATO, but it is not advisable to fire from it. But you can chamber and fire a .223 REM in a military M-16.
THis is because the chamber is built to withstand the military load.
A civilian M-16, like those made by Knights, Colt itself or any of the hundreds of private manufacturers that make M-16/variants - is usually a much better quality weapon than the military issue. -
If im not wrong. Its the different pressure from the two rounds. .223 Rem seems to be of higher pressure than 5.56mm
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It is very possible that with civilian .223 ammo, you can find some too powerful to be used on a military issue weapon as military-issue weapons are often mass-produced by the lowest bidder.
On the other hand, most 5.56mm military ammo are made to a certain standard of charge so they can be used on all kinds of 5.56mm military assault weapons anywhere in the world.
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On another (rather confusing) note:
There have been in existence for over 2 decades TWO different standards of military 5.56: the M193 and the M855.
The M193 is the OLD round with a 55-grain bullet made for earlier generation weapons like the M16A1, M16S1 and also our Ultimax-100.
The M855 is the NEW NATO-standard round with a heavier 62-grain bullet that also has a penetrator tip made for the next generation weapons like the M16A2, M249 Minimi and SAR-21.
Because the NEW M855 bullet is heavier, the weapon needs a different barrel twist.
Weapons made for the OLD M193 ammo won't work well with the NEW M855 ammo.
However...
Weapons made for the NEW M855 ammo can handle BOTH the OLD M193 and NEW M855 ammo equally well.
For example the M16A1 is made for the M193 - CANNOT handle the M855 ammo well.
The new M16A2 is made for the M855 - can handle both the M193 and M855 ammo well.
I think SAF standard is apparently still the M193 (Can someone confirm?) as we still use a lot of M16S1.
The SAR-21 can hadle both the new and old rounds. -
Projectile differences.
The increase in projectile length, weight, and configuration of the M855 bullet requires different twists in the barrels, lands, and grooves to stabilize the bullet in flight. The M16A1 has a 1:12 barrel twist (the bullet rotates once for every 12 inches of travel down the barrel). The M16A2/A3/A4 and the M4 carbine has a 1:7 barrel twist (the bullet rotates once for every 7 inches of travel down the barrel).
The M16A1, with its 1:12 twist, does not put enough spin on the heavier M855 bullet to stabilize it in flight, causing erratic performance and inaccuracy for training or full combat usage (30.48- to 35.56-centimeter shot group at 91.4 meters and 72-inch shot group at 274.2 meters).
Although firing the M855 cartridge in the M16A1 rifle is safe, it should only be used in a combat emergency, and then only for close ranges of 91.4 meters or less.
Full article read here:
http://www.jimwardrip.com/firearms/556_Ballistics.htm -
So the SAR21 being issued out has the twist rate of 1:7"?
I believe that the length of the round determines the rifling required.