223 vs 5.56 cases

N

Nathan

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Gun Digest Article
In this article, the author talks about military brass having less capacity and unsafe pressures.

I load with mixed brass and have not seen pressure signs or group spreads that support this claim.....what have you seen?
 
Nathan wrote:
In this article, the author talks about military brass having less capacity and unsafe pressures.
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A thicker case should weigh more than a thinner case.

As it turns out, I was processing 216 rounds of mixed range brass, so I went to the bench, pulled a sample of LC15 5.56 brass and a sample of Remington .223 commercial brass and weighed them. The average of the LC brass was 2 grains heavier than the Remington brass. The sample cohorts were small and the result is not intended to be definitive, just indicative of a difference. Still what we can take away from this is:
  • Military brass is indeed heavier than some Commercial brass.
  • The difference in weight suggests some part of the military case is thicker than its civilian counterpart.
  • The difference, however, was about 2% of case weight, so the additional thickness of the case is minimal.
  • Whether the volume reduction attributable to a 2% increase in weight is enough to cause a significant increase in chamber pressure is open to question as it would depend on the powder, primer and bullet used in the load.

My own experience across 38+ years of loading 223/5.56 with near-maximum loads of IMR-3031, IMR-4198 and Winchester 748 in both 223 and 5.56 brass has been that neither showed any pressure signs nor did one type of brass exhibit a noticeably shorter life than another.

Could a load developed to reach, but not exceed, maximum pressure in a commercial 223 case exceed SAAMI maximum pressure when loaded into a military case? Yes.

But the caution is not limited to the question of military versus civilian brass and the Gun Digest author's sweeping pronouncement about the capacity of 223 versus 5.56 brass is not well-founded.

I also weighed a sample of Wolf commercial brass (headstamped 223 Rem) and found it to be about 2 grains heavier than the LC15 5.56 brass suggesting it had a correspondingly lower capacity than the military brass. This is why all the reloading manuals advise reloaders to re-start load development when they change any component. What I take away from this is that if you are going to be shooting maximum loads, then it would make sense to sort your brass by headstamp, develop the load using the cases with the least capacity (by weight or water testing) and then transfer that recipe to the other brass from headstamps that had slightly larger case capacity.
 
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A couple of other exceptions I would take with the Gun Digest article you linked to are:
  • The blanket recommendation to use small base dies in semiautomatic rifles. In fact, many semi-automatic rifles have generous tolerances and so don't need small base dies and using small base dies where they are not called for simply overworks the brass and may shorten its life. I have a set of RCBS standard (not small base) dies that I use to load for five different 223/5.56 rifles and I have never had a problem with rounds from them chambering once they were properly adjusted.
  • The shilling for Redding and their bushing dies to generate adequate neck tension to avoid bullet set-back. Other manufacturers also make bushing dies, why is Redding singled out?
  • Also, again in 38 years of loading for 223/5.56 I have never had a bullet set back using conventional dies.
I think some of the comments at the bottom of the article adequately sum up most of the article's shortcomings. What would concern me is the author runs an ammunition manufacturing business and is selling people ammunition he has loaded based on some of the fictions he is perpetuating.
 
I hesitated to post on this thread as there is so much information and misinformation on this very subject that I didn't want to go down this rabbit hole. But, I guess since I load thousands of .223/556 and 7.62x51/.308 cases every other month....

5.56x45 cases (LC) and commercial .223 really do not have any more case variability than there exists between different brands of commercial brass. I.e. the average weight difference between federal, win, and remington will be similar to the difference in the weight difference between them and Lake City. So, if it is safe in commercial mixed headstamp brass, it will be fine in Lake city.


7.62x51 on the otherhand IS different. I have checked internal case-water volumes of once fired commercial brass and Lake City and found that there is several grains difference. I don't have the notes in front of me but I seem to remember it being about 3 grains. I have confirmed also that loads I have made that worked in remington and federal brass at maximum pressure would pierce primers in Lake City brass. My Federal GMM clone load had to be reduced from federal to lake city brass in my AR-10.

So, in summary, 556x45 isn't anymore variable than .223 mixed HS lots, but 7.62 is a bit different. But, if you are loading near the bottom or middle of the charge range, it won't matter much with respect to safety.
 
Yes. It's a 7.62/.308 problem. .30-06 commercial and military are much closer. In 5.56/.223, the difference is virtually non-existent. I once took a bunch of .308 and 7.62 brass and tried to predict case water overflow capacity from the weight. The accuracy of the predictions of differences in capacity was about ±20%. This is because you have a tolerance span of 0.008" in diameters, and when you widen a head without changing its front-to-back thickness, you get a weight increase but no change in capacity.

This article shows measured case water overflow capacities of various 5.56 and .223 cases if you scroll down to the third table (just before Powders). Interestingly, the Lake City 2006 brass has the most space in this sampling.
 
I have seen a difference in case volume , using Winchester brass in 308 . My charged filled the case to the base of the neck , using the Federal brass the same charge filled the case to the top of the case neck . I reduce the listed charge by 1 grain when using thick brass . See if the charge is higher on the case from .223 to 5.56
 
@hdwhit...thanks for your analysis. I was thinking the same. Are there no editors anymore? No requirement for technical accuracy?

I knew the small based die and bushing die stuff was bs. My awareness flag should have been up....more.
 
I sort my 223.5.56X45 brass by manufacturer, date, and weight. Military brass can vary highly depending on who makes it. I've weighed cases that were 92 grs up to 108 grs. The heavier ones were oddball military cases. Most commercial brass is around 95-96grs as well as a lot of LC brass. I've also seen pretty wide variations in weight with Remington commercial brass so I don't lump them together without weighing them. A load worked up in a 92-93 gr case is gonna show higher pressures if loaded into a 108gr case. My weights are based on a once fired brass with the spent primer still in the case unsized & untrimmed as found on the ground.
 
What I have seen is when loading to velocity, it takes on average, 0.5 grains less powder (25.0 vs 25.5) to achieve similar velocity in 5.56 spec cases vs domestic commercial cases.
This would indicate that if loading to the max in commercial cases, changing to mil-spec cases would/might kick you into dangerous levels. I see similar results between CCI 400 and CCI 41 primers-about 1/2 grain to get similar velocity.
 
308 yes, WW brass weighs 20 grains less than most surplus.

I could never see much difference between 223 commercial and 5.56 brass in terms of capacity or weight.
 
I hesitated to post on this thread as there is so much information and misinformation on this very subject that I didn't want to go down this rabbit hole.
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Me to and thought "not again" how ever

I agree with Unclenick and others that say the issue mostly lies in the 308 cases .

In 5.56/.223, the difference is virtually non-existent.
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I how ever don't agree with this . To say "virtually non-existent" would seem to indicate there is no need to worry about mixing NATO or 223 brass . Now that may be true with 223 brass but I still hesitate to believe that . I know it's not true for military brass . I don't have my notes in front of me but I did some mixed case test using IMR-8208xbr and did see the cases being filled to different levels when using NATO brass . In one case/head stamp the powder almost overflowed the mouth while most others were filled to the base of the neck .

I hesitate to say what head stamp that was but want to say CBC ( went and checked notes and they were CBC cases ) . I did chrono those loads that almost overflowed the cases and they shot on avg 100+ fps faster then the rest of the mixed cases and that mixed brass lot had very high ES/SD . I also did a case volume test using H2o and the CBC cases had over 1 full grain less capacity then the others and might have been more but can't find that note right off hand .

I then ran that same load in FC only cases and it shot much more consistently with a tad bit better accuracy . These test were done with Winchester 55gr FMJ-BT bullets through standard 16" CL barrel so accuracy was not expected to be great but I believe accuracy improved when using all the same head stamped cases

I th
 
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I don't shoot military ammo in any of my rifle's, never have. But I've used a lot of military brass in 30-06 and 308, wouldn't phase me to shoot a military round in a commercial rifle. This business with the 223/5.56 has been around the barn a lot. Here's the deal if you simply reload the stuff, and It would not bother me to fire a 5.56 in a commercial rifle. All of the 223/5.56 case's vary to some degree. In the past Remington case's were heavier than Winchester and Norma heavier still. What that means is inside capacity is changing and the heavier brass might develope pressure sooner than the lighter brass. No big deal, if your reloading start low and work up. Start low and work up fix's different problem's in handloading. In factory ammo. as I said I don't shoot miliraty loaded ammo in my rifles, I like to achieve a certain level of accuracy and don't believe military bullet's will get me there. But the brass is a differen't story. I've used LC Match brass in 308 and necked down to 243, great stuff. Now I use a lot of FA49 brass in my 30-06 and it works, all I can say for it. Also use a lot of LC brass, not match , in my 308 and it's fine. I can about guarantee you that shooting 5.56 in your 223 will work fine. what might happen is that it certainly may run at higher pressure, I don't know, but it will work fine. Over the years something I have found with most reload data, especially older data, is that Max loads may be max but I have exceeded them a good number of time's without problem. I do not recommend other's do it though, you have to have an idea what pressure sign's to look for. Food for though, if the 5.56 rounds are so much hotter than 223 rounds, I would think the 223 rounds won't cycle the action on a AR rifle! I suspect they do!

The safety of a round is probably the same as the requirement's on a bridge. To rate a bridge, it must be capable of handling much more weigh than is posted, used to know what that was. I would certainly suspect rifle cartridge pressure are determined the same way. Say 65,000# is posted as max but blow up is well beyond that in a good commercial action. If a military round will fit properly in a commercial I seriously doubt it will cause a problem! Imagine the liability is someone's rifle blew up shooting a cartridge that properly fit's it!
 
I just realized I never put the link to the article with case data into my last post. I have put it there now. Here it is again. Scroll down about 1/3 of the way to the third table (first table is so short you can miss it) just before the start of the discussion of powders.
 
5.56 brass
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When I size 223 Remington cases and 5.56 NATO they all come out of the die as 223 Remington. I know; but I do not mix head stamps, I do not mix years when it comes to military cases, I do not seat the bullets to, at or into the lands. I want my bullets to have that running start, if I have a rifle that does not shoot straight and or does not like 'that jump; it does not get shot.

And then there is that thing about weight, I am the only reloader that finds fault with all of the cute saying, again, I keep my cases separated and I do not mix head stamps.

F. Guffey
 
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I would stay a little bit off from the max load because the brass is slightly thicker. But once run through a .223 rem die and trimmed will be the same dimension as the .223 brass with just a little less powder capacity inside. I use a lot of this brass too because let's face it who is gonna pay $40 for 100 brass when you can get a thousand for that price. I have not any trouble with my Savage axis and it shoots 1/2" groups using this brass. I'm running a bout 1 grain below max with H335. For safety start a bit lower than that. But it works fine in my rifle using the mixed brass
 
No one is arguing that there's a difference in outside dimensions on either new or re-sized 5.56/.223 brass--there isn't. Thicker brass results in less space INSIDE the case which must be accounted for by adjusting powder charges.
Indiscriminately loading a variety of case brands, headstamps, or specifications is NOT recommended. This is plainly stated in most reloading manuals--reduce the charge when changing ANY component.
 
i've been reloading .223/5.56mm brass since the late 1960s. Many so called "gun writers" are stuck on the myth that US military brass is thicker than .223 commercial brass.

i weight the cases for my accuracy re-loads. The best brass i've found is TW 67. Luckily i have oodles of that ammo. i will not use any non US 5.56mm cases.

For my plinking loads i mix head stamps and use 24.5 grains of IMR 3031 with a 55 grain Game King bullet or a 55 grain FMJ.
 
this thread comes at a interesting time since I am in the process of sorting through a box of range pickup 5.56 this week. So far this brass has just been cleaned,. annealed and full length resized and primer pockets uniformed. The cases have not been trimmed to a uniform length yet

I sat here and weighed 50 cases and weights were from a low of 90.7 to a high of 93.9 or a 3.2 grain spread. I have no empty non military cases to compare.

After I finish prepping the tub and get them trimmed I hope to sort out 50 to 100 cases with a plus or minus .1 spread for a bolt gun I am building. For plinking in a semi auto I would just load to a medium charge and shoot.
 
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