Author Topic: 223 Rem vs 5.56 Nato  (Read 3078 times)

Offline hd45hunt

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223 Rem vs 5.56 Nato
« on: March 11, 2010, 12:33:07 PM »
I did some searching around on the net and read about not firing 5.56 ammo through a regular 223 rifle due to chamber differences.  Being fairly new to reloading, my questions regards reloading 5.56 brass.  I have a couple of AR's and a couple of 223 chambered rifles (Keltec SU-16 and Savage 24V) and while I was sorting brass last night noticed I have a substantially larger amount of 5.56 brass w/various headstamps than I have 223.  Can you size/load 5.56 brass to be safely fired in standard 223 chambered rifles??  I'm thinking yes (maybe) with the right (lower end) loads, but wanted to seek further guidance from those with some more experience before attempting something along these lines.   Jim

Offline Pathfinder

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Re: 223 Rem vs 5.56 Nato
« Reply #1 on: March 11, 2010, 01:46:55 PM »
There is a minute (ca. 1/10,000 of an inch) difference in case sizes IIRC.

The bigger issue is pressure, which for the 5.56 is higher than for the .223. IMHO, if you do load a 5.56 case, assuming the dimensions are trimmed for .223 use, and only use .223 reloading data to make sure you keep the pressures down to .223 specs, you should be good to go.

I would also check with a reloader in your area, one with experience in reloading both so they can show you how to do it safely.

Offline hd45hunt

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Re: 223 Rem vs 5.56 Nato
« Reply #2 on: March 11, 2010, 02:47:28 PM »
That is what I had in mind using the 5.56 cases, trimming to 223 specs and loading to 223 specs with something in the 40-55 gr range.  May be a non issue is I can get some more 223 brass, just short on it at this point, with lots of extra 556.

Offline Duc1

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Re: 223 Rem vs 5.56 Nato
« Reply #3 on: March 13, 2010, 04:07:48 PM »
I've been using 556 brass trimmed to 223 specs for years and have had no problems.  I've always started at the lowest load first and work my way up keeping an eye for signs of pressure.  It seems that the Hornady manual that I use is more conservative than many others having a lower max load.  I've had to swage the crimped primer pockets also.

Offline Steve Cover

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Re: 223 Rem vs 5.56 Nato
« Reply #4 on: March 17, 2010, 02:50:20 PM »
I've been using 556 brass trimmed to 223 specs for years and have had no problems.  I've always started at the lowest load first and work my way up keeping an eye for signs of pressure.  It seems that the Hornady manual that I use is more conservative than many others having a lower max load.  I've had to swage the crimped primer pockets also.
I have done the same for years too.
The only Caveat is that military brass is a bit thicker walled than commercial brass. 
Because this causes a smaller inside case volume, the max listed pressures for 223 brass will be too hot for the military brass.
Since the best loads are usually 70%-85% of max, this has never been an issue for me.
Just be aware of the difference and you should do well.

Steve