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Thread: Does it really matter 223 vs 5.56 - 308 vs 7.62x51

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    Does it really matter 223 vs 5.56 - 308 vs 7.62x51

    I did some google searches and see that there is a difference between:

    223 and 5.56

    308 and 7.62x51

    Given a choose for brass which would you prefer out of the 2 groups?

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    Re: Does it really matter 223 vs 5.56 - 308 vs 7.62x51

    5.56 NATO ammo not recommended for 223 chambers.

    308 Win (high pressure loads) not recommended for 7.62 NATO chambers.

    Disclaimer:

    There are gabazillions of people who mix and match and are still around to talk about it.

    Chris

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    Re: Does it really matter 223 vs 5.56 - 308 vs 7.62x51

    Go with a wylde 223 chamber, it shoots them all very well. There are more than
    several .223 and 5.56 chambers but the main difference is the longer throat and freebore in the 5.56.

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    Re: Does it really matter 223 vs 5.56 - 308 vs 7.62x51

    Apparently those "WARNINGS" are written by the same folks that predict global warning will kill us all in 300 years and we have hours to save ourselves by giving them money.

    If there was a problem you would see all kinds of warnings on the box the rifle came in, stamped on the barrel, written in the instructions, sent to you via registered mail when you send warranty card in and there would have been massive recalls. Plus you would have to sign a "I done been told" statement when you buy the rifle.
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    Re: Does it really matter 223 vs 5.56 - 308 vs 7.62x51

    My Colt says 223 on the lower and 5.56 on the upper. So I agree with Hummer and consider them close enough to ignore.
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    Re: Does it really matter 223 vs 5.56 - 308 vs 7.62x51

    Here's a clue: get a micrometer or a .001 dial caliper and put it at the value of the biggest of those real CHAMBER dimension differences. Hold that tiny slit up to the light and see how tiny it is.

    THEN put some real ammo's measured dimensions into the mix and you'll see that the regular clearance between case shoulder and even a min-spec chamber is pretty big compared to the "difference".

    I gave up years ago trying to locate a reliable case/ammo drawing with *tolerances* on the web. All the reloading manuals have the MAX dimensions, but I haven't been able to find a drawing with the MIN dimensions. But I can tell you that when the differences between a NATO chamber and a SAAMI chamber are, say .0015 in one direction, the ammo usually has triple that amount of clearance from the chamber anyway.

    IMO, the only place it makes a difference is the throat on true .223s vs. 5.56 (now) NATO chambers. NATO ammo and reloads with NATO-profile ogives *will* spike dangerous pressures in SAAMI .223 chambers.

    You will also find that almost every discussion of military ammo vs. SAAMI ammo pressures in .308/7.62x51 are comparing newer SAAMI Piezo transducer readings with older copper crusher readings. Even copper vs. copper from the old days are NOT comparable, because one test used cases with a hole opposite the crusher piston, while the other used intact cases. For copper vs. piezo differences that are BOTH "in spec" for pressure, just consult the latest Hodgdon reloading guide with all the powders in it, and see how the piezo PSI values are thousands of "psi" higher than the CUP crusher numbers.

    In .308, the only place it is likely to make a difference is out of spec reloads in some odd bolt guns converted from EARLY Mauser actions originally made for lower-pressure 1890s ammo. Everything else has such a huge safety margin, whatever real difference exists between SAAMI and NATO pressures is of no consequence.

    In fact, I've run QuickLOAD on several VARGET and IMR powder reloads supposedly only for bolt guns and unsuitable for semiautos, and found that the predicted port pressure (with variables matching reported velocities) still very much okay for M14 gas systems.

    No one has yet to tell me the AR10-style rifles' specifications for port pressure, though. I'd love to see it with the traditional military style of "nominal number +/- tolerance spec". I can tell you this, though--I tested light loads that failed to cycle an inch-pattern FAL with the gas system adjusted to full power, that still cycled just fine in an M1A.

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    Re: Does it really matter 223 vs 5.56 - 308 vs 7.62x51

    Originally Posted By: 2shot1kill
    223 and 5.56

    Given a choose for brass which would you prefer out of the 2 groups? [/quote]

    I like Lake City brass in 223/5.56, and Winchester Brass in 308/7.62 although, here, Lapua brass is notably excellent. I get my LC brass from Black Hills reload boxes (range pick up), and my Win brass in cellophane packages.

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    Re: Does it really matter 223 vs 5.56 - 308 vs 7.62x51

    There are good gas gun reloading sections in some of the new manuals. It is a good
    idea to use them. The .223 chamber is a bit shorter in the freebore. The higher pressured nato round can and does stretch into the throat and pinches the bullet
    spiking the pressures. Winchester had a good article on it on their website. You can
    break a bolt with this problem before any gas ever reaches the gas port.

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    Re: Does it really matter 223 vs 5.56 - 308 vs 7.62x51

    A number of years ago somebody at Remington got a sandspur in their jock strap over this same thing and I got a call from one of my contacts at Ilion who asked me if I could round up some M193, SS109, etc of several lots as this pending catastrophe had been surfaced. I got together about a hundred rounds and had it all packed up ready to send and called them and said it was ready. My friend said he would get me an address of where it was to be sent and I didn't get a call back. I asked him several months later and he said it was determined that there was nothing to it and that was a relief because worrying about that and global warming was just too much for my nerves.


    Did some more research. I did not take into consideration there is a ton of foreign 5.56 flooding the market of questionable quality. While I can't find anyone that has had problem with US production 5.56 I understand this foreign stuff (not NATO qualified) can get real iffy even in 5.56 chambers. I won't buy any of the foreign stuff because of the steel jackets but I also understand some of the case dimensions are small and their case draws are thin and there has been problems with 5.56 case failures with the case letting go in the middle.
    I suspect I have personally fired over 10,000 rounds of US milspec ammo in bolt guns and never had reason to doubt the safety but the introduction of foreign stuff under the heading of 5.56 puts a whole new problem on the scene. As well I have seen numerous individuals shooting US 5.56 (which is NATO qualified) in bolt guns with no problem.
    I also know the US gun industry has had problems with foreign military type ammo in US rifles of several calibers thusly it would be prudent to take into account that we don't know the quality of foreign ammo as it is not generally made to NATO STANAG.

    I have also shot US milspec ammo in my 7615 Remmey without a hitch as well as my 700 I had and Model 70 Winchester to include SS109 and M855 with no problem.

    Thusly be careful getting real deals. You may not be doing yourself a favor by going cheaper.

    I know the Border Patrol got some foreign 308 hunting type ammo about 25 years ago and it was so hot their Rem 760s did not want to open the action. I tested some and got flat primers in bolt guns but never gave any hard opening indications. They never had a action fail, just did not want to open easily.

    I had some Rem 30.06 Match a number of years back and could only shoot it in cold weather. In hot weather it gave pressure signs but winter time it was fine. I finally made a note to pull it down and reduce charge on any more of it I wanted to shoot.

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