5.56×45 NATO - .223 Remington. Same but different?

[urban]

I have a new Howa 1500 in .223 which I shot for the first time on Sunday. I shot both .223 (GGG .223 Rem Match 69gr) and 5.56 (Magtech 62gr). The .223 was fine, the 5.56 showed cratered primers and after about 30 rounds one of the primers let go completely. So in this rifle at least, it doesn't seem wise to continue shooting 5.56.

Some of the 5.56 was quite difficult to chamber, which I don't really understand given that the case dimensions of 5.56 are supposed to be identical to .223.

 

[Eddie P]

I have a new Howa 1500 in .223 which I shot for the first time on Sunday. I shot both .223 (GGG .223 Rem Match 69gr) and 5.56 (Magtech 62gr). The .223 was fine, the 5.56 showed cratered primers and after about 30 rounds one of the primers let go completely. So in this rifle at least, it doesn't seem wise to continue shooting 5.56.

Some of the 5.56 was quite difficult to chamber, which I don't really understand given that the case dimensions of 5.56 are supposed to be identical to .223.

Try pulling a bullet from the magtech and chambering the case. If it's fine, then your problem is due to the shorter freebore of the 5.56.

 

[williamwansbeck]

More correct, although of less relevance today to us since the Tory handgun ban is the very real difference between 9mm Luger as loaded in the USA and 9mm Parabellum as loaded in the UK and more especially British 9mm 2Z. But that's water under the bridge in 2023.

2Z a bit bumpy in a Browning p35.

 

[enfieldspares]

2Z a bit bumpy in a Browning p35.

Yes! I remember a range morning in Germany as a guest in my late teens with 22 Royal Signals during Exercise March Hare in maybe 1973 when we were told we'd, six of us, we'd a whole tin of 9mm 2Z to "dispose of". Which was about a thousand two hundred rounds. We started with the Hi-Power then went on to the Stirling and ended firing the the things in fully automatic short bursts from the hip at twenty-five metres. Just like they did the Sten in the war movies. LOL!

Even with a sandbank directly behind the Figure 11 targets (so you could see the strike and walk the gun onto it) it was very very difficult to get anything like a favourable number of rounds on the target. Fully automatic short bursts from the shoulder, aimed, were easy (indeed that short bursts from the shoulder was how the thing was taught to be used at night) but from the hip and in daylight?

Those movie men with their Sten cutting down swathes of Germans like so much scythed wheat at harvest must have had extra special shooting skills we lacked! In the High Power, 2Z, it was a bit bumpy, yes! Ejected well though!

 

[The Singing Stalker]

 

[NP435]

Consider this, the real change between the two cartridges is Nato spec 5.56 is loaded to produce penetration of a NATO helmet at 800 yards. Thus the throat dimensions are longer in service rifles and NATO spec pressure testing is not the same as C.I.P or SAMMI methods. Reloading data does exist for NATO spec performance in .223 data. Proof loads are vastly higher pressure yet. I have zero worries about NATO spec ammo in my .223 SAVAGE 110 or RUGER Ranch Rifle.

 

[Andy RV]

How’s many shots through a 223 until the throat is worn to 5.56 dimensions?…

 

[williamwansbeck]

Yes! I remember a range morning in Germany as a guest in my late teens with 22 Royal Signals during Exercise March Hare in maybe 1973 when we were told we'd, six of us, we'd a whole tin of 9mm 2Z to "dispose of". Which was about a thousand two hundred rounds. We started with the Hi-Power then went on to the Stirling and ended firing the the things in fully automatic short bursts from the hip at twenty-five metres. Just like they did the Sten in the war movies. LOL!

Even with a sandbank directly behind the Figure 11 targets (so you could see the strike and walk the gun onto it) it was very very difficult to get anything like a favourable number of rounds on the target. Fully automatic short bursts from the shoulder, aimed, were easy (indeed that short bursts from the shoulder was how the thing was taught to be used at night) but from the hip and in daylight?

Those movie men with their Sten cutting down swathes of Germans like so much scythed wheat at harvest must have had extra special shooting skills we lacked! In the High Power, 2Z, it was a bit bumpy, yes! Ejected well though!

The SMG a suprisingly good tool if held like a little rifle on single shot.

 

[KimE]

Perfectly safe, 308win chamber is rated at a higher pressure than 7.62

You may have potentially have the reverse issue if shooting some 308 in some 7.62 chambers

My Tikka 308w does not like 7,62NATO ammunition high pressure and a large spread.

 

[Kidderminster steve]

How’s many shots through a 223 until the throat is worn to 5.56 dimensions?…

I thought they were the same apart from pressure? 5.56mm NATO was based on the .223 if not mistaken. All 5.56mm NATO eating firearms can take .223 but not the other way around. It's like old standard 9mm firearms and military issue 9mm which is plus "P". Higher pressure cartridge. The actual brass and barrel designed to take more pressure. I'm an amateur compared to nearly everyone on here so could be wrong but some old information does stick in my brain cells occasionally.

 

[Kidderminster steve]

I thought they were the same apart from pressure? 5.56mm NATO was based on the .223 if not mistaken. All 5.56mm NATO eating firearms can take .223 but not the other way around. It's like old standard 9mm firearms and military issue 9mm which is plus "P". Higher pressure cartridge. The actual brass and barrel designed to take more pressure. I'm an amateur compared to nearly everyone on here so could be wrong but some old information does stick in my brain cells occasionally.

Not saying only military 9mm firearms can take plus P as is not the case nowadays. Most modern 9mm firearms can take plus "P". It says in instruction manual and sometimes on the reciever. 124grain "P" rounds have a snap ! Standard British army are 115grain plus "P". Anyway I'm ranting. Apologies.

 

[Heym SR20]

These days how much 5.56 Nato actually makes onto the civilian market?

Any surplus ammo from western militaries has gone to the Ukraine. Any new production is filling up NATO Arsenals if its not being sent to Ukraine. The middle east is also using huge amounts of ammo.

Even with the 223 designation there are big variations especially between the older 1 in 12” and the newer 1 in 8” twists.

 

[Laurie]

I thought they were the same apart from pressure? 5.56mm NATO was based on the .223 if not mistaken. All 5.56mm NATO eating firearms can take .223 but not the other way around. It's like old standard 9mm firearms and military issue 9mm which is plus "P". Higher pressure cartridge.

There is a huge amount of disinformation on this issue. For a start, the two MAP (Maximum Average Pressure) ceilings quoted are measured differently and cannot be directly compared. Both use Piezo crystal electronic technology, but NATO specifies CIP methodology which gives different (higher pressure readings) results to that of the US SAAMI commercial ammunition method. (That's why the CIP MAP for 223 Rem is the same as 5.56, ie a bit above 62,000 psi vs 55,000 psi for SAAMI.)

Dimensionally, both rounds are identical. Also, unlike 7.62 vs 308, much 5.56 brass does not run thicker case walls / reduced internal capacities than commercial 223. US Lake City Army Ammunition Plant 5.56 is for example at the top end of 223 for capacity (which reduces pressures). Some 5.56 cases such as the German MEN that HPS used to sell are heavy/low capacity though and standard 223 loads need to be reduced.

The big (really only) difference is in chambers, specifically the throat length and the leade (the bevelled transition into the rifling) length/angle. 5.56 has a much longer throat and a longer, shallower angle transition into the rifling lands. The 'freebore' for the 223 is a mere 25 thou', very short indeed, that of 5.56s much longer. That reduces pressure and the cartridge can be loaded more heavily within safe pressures. (Bullets are also seated out much further in single shot use which is why American Hi-Power XTC competition AR-15s accept the 80 gn Sierra MK at 2.550-inch COAL single-loaded for the 600 yard match stage while a true 223 SAAMI chamber wouldn't allow a round so loaded to be chambered. The Standard SAAMI 223 Rem has a maximum COAL of 2.260".)

The widely used '223 Wylde chamber' seen in many civilian ARs including that of nearly all of our CSR competition straight-pull rifles is basically a 5.56 chamber, but with the throat dimensions / clearances reduced to enhance accuracy. These rifles accept standard M855/SS109 specification NATO 62gn ball ammunition fine without anything breaking. In F/TR type long-range competition rifles which are single-loaded, yet longer chamber throats are employed to handle still longer >80gn bullets. I ran one such for years and the COAL with a 90gn Berger VLD was 2.9-inch, slightly longer than standard spec 308 rounds.

 

[Eddie P]

These days how much 5.56 Nato actually makes onto the civilian market?

Any surplus ammo from western militaries has gone to the Ukraine. Any new production is filling up NATO Arsenals if its not being sent to Ukraine. The middle east is also using huge amounts of ammo.

Even with the 223 designation there are big variations especially between the older 1 in 12” and the newer 1 in 8” twists.

Some companies, ie GGG sell new 5.56 nato spec ammo as new, not surplus from old stocks.

 

[nic531]

wish I could use GGG..... the 62gn bullet just does not stabilise well in my Wylde chamber. have to use 69 or 75gn