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Old May 23, 2013, 12:02 PM   #1
rebs
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223/5.56 brass difference ?

I have been reloading all LC 5.56 brass, what will be the difference be if I start reloading Winchester 223 brass ? Will there be a big difference in accuracy or will I have to work up loads all over again ?
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Old May 23, 2013, 12:21 PM   #2
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.223 vs 5.56

I bulk load .223/5.56 and even stopped sorting military vs commercial cases. The only difference in these rounds is the chamber of the weapon with the 5.56 having a longer throat. Obviously if you were bench rest compeditive shooting you might gain .25 moa by match prepping cases. For general varmit and target shooting I get .5" moa in a couple of my .223/5.56 weapons. All shoot .75" or better. I load to (5.56) 2.25" OAL specs for the AR15 but they shoot just fine in bolt guns as well.
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Old May 23, 2013, 02:24 PM   #3
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LC brass may be a little thicker, which reduces case capacity. I use the term "may" carefully.

I've personally never noticed any difference in how either loads or shoots, but there are plenty out there that swear military brass is thick enough that it can jack with your pressures using the same loads you would in a commercial brass load.
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Old May 23, 2013, 02:35 PM   #4
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If you do an OCW load work up it should give similar results regardless of head stamp. Espcialy in .223 Rem. I shoot a Savage Model 12 FSSV that gives half MOA or better with mixed head stamp brass with the bipod, and a sand bag under the rear of the stock. I tried all matching head stamp, and mixed in testing. The results were so close I run mixxed head stamp. The pain to pay off factor was the final decider in that for me.

I am not saying that you will not get better accuracy if you do not sort by head stamp, and do all of the other things like water weighing cases, and full match prep. Usualy to be able to see much of a differance it would take a mechanincal rest in an indoor range with perfect conditions to see a great improvement in most cases.
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Old May 23, 2013, 05:38 PM   #5
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All of my LC brass which is 05-09 headstamp consistently holds 1 gr additional powder (IMR4064 or Varget) over any of the Federal or Remington .223 cases. IMI cases are the same; almost 1gr extra capacity.

I just went through this exercise last night comparing case volumes; was curious about the potential pressure differences. I've got one manual that says 24.7gr of 4064 is a compressed load another says 26gr; I don't see compression until I get to 25.5gr though in these LC. It appears it's all a big crapshoot.. so tomorrow when I OCW test this batch, I'll be watching very closely for pressure signs. Chambered 5.56, so I'm not too concerned, but this is only the 2nd time I've reloaded for this rifle.
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Old May 23, 2013, 06:25 PM   #6
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Quote:
Will there be a big difference in accuracy or will I have to work up loads all over again ?
Maybe, but I highly doubt you will notice any difference at all.

That said, remember the rule , anytime you change a component you should drop the charge down and work back up.
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Old May 23, 2013, 10:59 PM   #7
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Not a pro here but . . .

I know that the new Mossberg MMR has trouble shooing 5.56 but not 223. It was designed for 223. Maybe someone who knows more about these almost identical cartridges can tell us more but if you read up on the Mossberg MMR it's pretty clear that they do not shoot 5.56 well and run just fine with 223.
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Old May 24, 2013, 06:39 AM   #8
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Quote:
I know that the new Mossberg MMR has trouble shooing 5.56 but not 223. It was designed for 223. Maybe someone who knows more about these almost identical cartridges can tell us more but if you read up on the Mossberg MMR it's pretty clear that they do not shoot 5.56 well and run just fine with 223.
I think you are confusing 5.56 Factory ammo with Reloading fired 5.56 and 223 cases. The OP is not talking about handloading to 5.56 pressures, he is talking about the brass case and how different brands of brass will affect accuracy.

Factory 5.56 ammo was never mentioned.
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Old May 24, 2013, 08:52 AM   #9
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5.56 vs .223 Rem.

The 5.56 chamber has a longer throat than .223 rem. If you load some .22 cal heavy bullets longer than 2.25" you can create high pressure by jamming the bullet into the lands of a .223 chamber.

The Chambers

The significant difference between the .223 Rem and 5.56 NATO lies in the rifles, rather than the cartridges themselves. Both the .223 and 5.56 rounds will chamber in rifles designed for either cartridge, but the critical component, leade, will be different in each rifle.

The leade is the area of the barrel in front of the chamber prior to where the rifling begins. This is where the loaded bullet is located when a cartridge is chambered. The leade is frequently called the “throat.”

On a .223 Remington spec rifle, the leade will be 0.085”. This is the standard described by the Sporting Arms and Ammunition Manufacturers’ Institute, Inc. (SAAMI). The leade in a 5.56 NATO spec rifle is 0.162”, or almost double the leade of the .223 rifle.

A shorter leade in a SAAMI spec rifle creates a situation where the bullet in a 5.56 NATO round, when chambered, can contact the rifling prior to being fired. By having contact with the rifling prematurely (at the moment of firing), chamber pressure can be dramatically increased, creating the danger of a ruptured case or other cartridge/gun failure.

The reverse situation, a .223 Rem round in a 5.56 NATO gun, isn’t dangerous. The leade is longer, so a slight loss in velocity and accuracy may be experienced, but there is not a danger of increased pressures and subsequent catastrophic failure.
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Old May 24, 2013, 09:47 AM   #10
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Thank you I appreciate all the replies.
From what I read here the OAL can be 2.260 with either 223 or 5.56 case, right ?
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Old May 24, 2013, 12:21 PM   #11
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Current SAAMI standard calls for 2.125" to 2.260", so anything in there that suits the bullet should fit in a magazine. That's all the COL spec is for.

A number of comparisons of brass have been made, and with only a couple of exceptions, military and civilian .223 brass have about the same weight and capacity. I think the 6mmBR site has one table of measured comparisons. It's really only in the .308 Win/7/62 NATO that major case differences are common. Military brass is usually a little harder so it extracts reliably. Unfortunately, that means it wears out faster because it's a bit less malleable. A lot of owners of AR's and other self-loading .223/5.56 guns will only reload a total of 5 times (original load brings it up to 5 firings) before retiring them. But this depends how warm you load them and on the size of your chamber, etc., so you need to use some judgment there. Feeling inside a good random sample for a pressure ring growth with a dental pick or a small bend on the end of a straightened paper clip is a good idea to do on a regular basis.

Note that most bullet makers have a recommended COL for each of their bullets in each cartridge they are used in. If you name a particular bullet you are looking at using and it's one of the major brands, someone will look the recommended COL up in a databook and report it. Your chamber may prefer something else, but the recommended COL is a good starting place.
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Last edited by Unclenick; May 24, 2013 at 12:29 PM.
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