5.56 question

[Guest F0rd4x4xlts]

I was looking at ammo..whats the difference between a non standard 5.56x45 and a standard 5.56x45? Would both work in my AR or just one?

[JeffsSig]

May I ask where you saw "non standard" 5.56 ammo for sale?

[Guest F0rd4x4xlts]

http://www.policehq.com/Products/FC-223AE

[Reservoir Dog]

I have no idea what they are talking about. Maybe they are referring to a .223 Remington chamber as the "non-standard" 5.56mm chamber.

[Mike]

It's referring to .223 Remington and .223 wylde chambers.

[lowery100]

Yea, only saying it should be used in a 5.56 chamber not a .223. You can shoot .223 in a 5.56, however you should not shoot a 5.56 in a .223 chambered weapon. The Wylde chamber should be able to handle both safely.

[Guest F0rd4x4xlts]

Sounds good. Im fairly new to the rifle world so it was something i got curious about.

[PoofNoEyeBrows]

The difference is that 5.56x45 (military spec) does not comfort to SAAMI pressure specifications. Also of note is that often times 5.56x45 will have a longer throat in the chamber to accommodate longer heavy bullets. As noted above .223 is just fine in 5.56x45 and 5.56x45 is usually just fine in Wylde.

[netmindr]

So if the 5.56 has a longer throat, does that mean it will typically be less accurate with .223?

If so, when reloading .223, would it then be a good idea to adjust for the ogive of your particular bullet by manually chambering an unseated bullet to determine the best OAL for your gun's chamber to improve accuracy?

[Mike]

So if the 5.56 has a longer throat, does that mean it will typically be less accurate with .223?

Yes, but not by much.

If so, when reloading .223, would it then be a good idea to adjust for the ogive of your particular bullet by manually chambering an unseated bullet to determine the best OAL for your gun's chamber to improve accuracy?

If you do this be sure your OAL doesn't exceed the length of the magazine.

[Guest BungieCord]

There are several (nine by my count) dimensional differences between the .223 Remington chamber and the 5.56 NATO chamber. From the standpoint of accuracy, probably the most significant is the diameter of the freebore. It's larger by ~0.002" in the NATO chamber in the interest of reliable feeding but the extra wiggle room costs it in ultimate accuracy.

The .223 Wylde was created as a compromise because competitive shooters preferred the Remington chamber's accuracy but needed the NATO's longer leade so they could shoot heavier, higher BC bullets without giving up so much case capacity to the longer bullet's seating depth. And just for giggles, they specked the Wylde chamber to the NATO's higher pressure.

Here's the specs used by a few reamer manufacturers for all three cartridges.

[Dolomite_supafly]

The biggest difference between a 5.56 chamber and a 223 chamber is the throat or the amount the bullet jumps to get to the rifling. There are other differences but those are more about relaibility in a dirty enviroment than safe firing of the firearm.

In a 5.56 chamber there is a longer throat to allow the extra pressures of the 5.56 cartidge to dissipate some before hitting the rifling.

On the flip side a 223 chamber doesn't have the longer throat because it doesn't need to dissipate those extra pressures like the 5.56.

Now if you fire a 5.56, with its extra pressures, and do not have the throat for it pressures can spike well beyond 223 or even 5.56 pressures. Is it enough to blow a gun up? I can't say but the spike can't be good for long term durability. This is why I always say make sure you have a hardened bolt in your gun, they help ward off premature failure. I have never heard of a 5.56 blowing up a 223 chambered gun. Not saying it never happened or never will but I have never heard of it.

Now I have measured the throat on quite a few 223 only bolt guns. And every one of them has had a throat long enough to easily fire 5.56. As a matter of fact most of them had throats longer than 5.56 chambers.

The 5.56 chamber tends to be "looser" all the way around for reliability and as another person said this sacrifices potential accuracy.

The Wylde chamber is looser than even 5.56 chambers except the throat diameter is .224.

Dolomite

[Mike]

Now if you fire a 5.56, with its extra pressures, and do not have the throat for it pressures can spike well beyond 223 or even 5.56 pressures. Is it enough to blow a gun up? I can't say but the spike can't be good for long term durability. This is why I always say make sure you have a hardened bolt in your gun, they help ward off premature failure. I have never heard of a 5.56 blowing up a 223 chambered gun. Not saying it never happened or never will but I have never heard of it.

Typically the pressure spikes will blow primers out of the casing, causing failure in the triggers when they drop into the lower. In extreme cases they can blow out the casing itself.

Mike