Reloading 5.56?

[HELLSING]

I appologize if this has been asked before, I did a search and nothing came up in the forums also.

Anyhow. I use RCBS full length .223 sizing dies. I've always just reloaded .223 brass. Well, today when I was cleaning out my safe and putting some tax papers away I noticed I had a few boxes of 55gr. Independence 5.56 FMJ's and thought about going to the Range tomorrow and reloading this brass.

Can I use my .223 dies or do I need to get another set for 5.56? Or do they even make 5.56 dies?

 

[iouri]

There's no 5.56 dies. Dies are .223 (0.223" = 5.56mm). I think SAAMI spec is for 223, 5.56 is the chamber dimensions.

 

[Cdog]

The physical characteristics of the two rounds are the same. The difference lies in the rifles chamber dimensions.

Mr. Iouri is correct, the .223 FL dies are fine.

 

[BlueOvalBandit]

Same thing. Case dimensions between .223 and 5.56 are identical. 5.56 chamber have a different lead cut than .223. The lead is the part where it transitions to the rifling. There is debate on the pressure differences, NATO 5.56 spec is 62k psi max, SAAMI .223 is 55k PSI max, whether they're loaded to max is anyone's guess without piezo pressure sensors.

 

[vince_ross]

I'd use them too. I have two sets of .223 dies and one set says on the label .223/5.56

I think the casing thickness is also a hair thicker on the 5.56 to handle the higher pressures.

 

[TheTinMan]

Same thing. Case dimensions between .223 and 5.56 are identical. 5.56 chamber have a different lead cut than .223. The lead is the part where it transitions to the rifling. There is debate on the pressure differences, NATO 5.56 spec is 62k psi max, SAAMI .223 is 55k PSI max, whether they're loaded to max is anyone's guess without piezo pressure sensors.

IIRC those two measurements were done with different methods and aren't really comparable. However, my memory may not be perfect...

I can tell you that Clymer has different part numbers for .223 Remington vs. 5.56 Nato "Go" and "No Go" headspace gauges, just liek they do for .308 Winchester vs. 7.62 Nato. However, my impression is that the biggest difference between .223 and 5.56 chambers is in the leade, with 5.56 having a longer leade.

 

[WR Moore]

Depending upon what reamer brand you're looking at, a 5.56 x 45 mm reamer will have 0.020-0.030 more freebore than a .223 reamer by the same brand. The leade angle will also be slightly different as well as possibly different body diameters. None of which has any effect on loading the ammunition, so long as you stick to published .223 data.

Because the military chronographs at 78 feet instead of the SAAMI standard 15 feet, the maximum pressure for 5.56mm ammo needed to be raised to produce the specified velocity. As noted previously, that doesn't mean any specific lot of 5.56mm will actually produce that pressure.

 

[VMaxSplat]

It looks like the 556/223 die question has been well covered. One thing I'd add, the RCBS X-Die is great for high volume loading because it saves much time on case trimming after the initial trim to length.