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5.56 nato vs rem .223 differences

Discussion in 'Rifle Country' started by mookiie, Jun 23, 2012.

  1. mookiie

    mookiie Well-Known Member

  2. firesky101

    firesky101 Well-Known Member

    Good read, very informative.
  3. Mark-Smith

    Mark-Smith Well-Known Member

    Wow, that is really informative. I've read some of Andrew Tuohy's stuff before, but that takes the cake. Nice to see original first hand research instead of the same notions based on third or fourth hand bits being rehashed.
  4. jmr40

    jmr40 Well-Known Member

    Glad to see this. He basically confirmed what I've been saying for years. Pick up a dozen 30-06 rifles, measure the chambers, pressure test them with an assortment of ammo from various manufacturers and you will see just as much difference between them as you would between a dozen rifles chambered in 5.56 and 223.
  5. taliv

    taliv Moderator

    before we get all moist over the conclusion (though i applaud his testing) it is based on a sample size of ONE chamber labeled 223 and TWO chambers labeled 556.

    in other words, statistically,what he's done is completely meaningless.

    While I wouldn't really be afraid of shooting 556 in a 223, I'm NOT going to recommend it to others because it is possible to have a problem. In perfect conditions, you're probably going to be fine, but if it's raining, or 110* or you got a little dirt in the chamber, or you get some tolerance stacking that doesn't go your way, you could have a kaboom.

    Also, at just about every carbine course I go to, there's some poor dude with a 556 chamber that is popping primers with factory ammo. Inevitably, someone runs one of ned christiansen's hand-556nato reamer tools and out comes a bunch of metal shavings, which means the "556nato" chamber wasn't really 556nato, but as this article points out, somewhere in between. and it's always tighter, not larger, meaning higher pressure because (my opinion) chamber reamers are wear items and can only be used so many times. if you measured the first rifle and the last rifle made by a given reamer, i'll bet you see a big difference. and if you measured them with a strain gage, i'll bet you'll see a big difference as well. my point is this also happens on 223rem chambers, and if you get a tight 223rem along with higher pressure 556nato ammo... sure, they run "proof" loads through those guns at MUCH higher pressures, but you wouldn't want to run thousands of rounds... it's asking for trouble

    btw, i also have a strain gage that i tested a bunch of bolt guns with years ago. they're fun tools and the cheap ones are not that expensive. I think you'll find the graphs in the article and the ones on this page looks quite similar. :)


    I'd also recommend giving the dude who sells these a call. he is a wealth of info and fun to talk to.
  6. madcratebuilder

    madcratebuilder Well-Known Member


    With the excellent availability of both 5.56 and .223 there are no good reasons the use 5.56 in a .223 chamber.
  7. 303tom

    303tom member

    Here we go again, it`s just like the 7.62 NATO vs .308, is there a difference ? Basically NO...........
  8. gp911

    gp911 Well-Known Member

    Interesting article, thanks for sharing it.
  9. wally

    wally Well-Known Member

    Concerning .223 vs 5.56 and 7.62 vs. 308:

    In our lawsuit happy society, where you get sued because your coffee-to-go was too hot and scalded an idiot who spilled it in their lap, if there was a difference that mattered from a safety standpoint that any manufacturer would sell the "tighter" chamber?

    Conversely if there was a difference that mattered where are all the lawsuits and reports of damaged guns?
  10. taliv

    taliv Moderator

    yes of course. companies take calculated risks. look at the safety features and recalls on vehicles for proof of that.

    settlements always come with non-disclosure agreements.

    (i'm not saying there are lots of lawsuits out there. i'm just saying it's a bad assumption to say that there aren't any just because you haven't heard of them)
  11. pubthumper

    pubthumper Active Member

    By that same logic, the notion that ALL settlements concerning this issue have nondisclosure agreements, or even that a large percentage of them do, is also a 'bad assumption'.

    All things considered, there is obviously a difference in the rounds cited, just not one that matters much.
  12. wally

    wally Well-Known Member

    Sure for the terms of the settlement, but the fact of the lawsuit being filed and that there was a settlement instead of a judgement are a matter of public record in most if not all states as far as I know.

    In most states the standards of "proof" and guilt is mostly kangarro court which usually makes it cheaper to settle. Its how a slickster lawyer like John Edwards got rich and pushed up you wife's OB/GYN costs a whole lot.
  13. taliv

    taliv Moderator

    again, do whatever you see fit. just don't recommend to new shooters who don't know better, that they should utterly disregard all the SAAMI and mfg warnings, without offering some compelling proof.
  14. wally

    wally Well-Known Member

    I've offered lack of proof of a problem as evidence that it is just not a safety problem.

    I'll shut up about it and pass on the correction to all I speak to henceforth, as soon as you or anyone else can point me to an actual documented safety issue about 7.62 vs. .308 or 5.56 vs .223

    Or have secret courts and tribunals always been in effect unbeknown to me?
  15. MCMXI

    MCMXI Well-Known Member

    Two chambers labelled 223 and three labelled 556 if you include the data from Barnes but it's still a small sample. I'm curious as to how accurate the strain gauge method is compared to the industry standard method using a calibrated conformal transducer.
  16. mookiie

    mookiie Well-Known Member

    I thought it was interesting that one of the 556 chambers posted such high pressures compared to the other 556 chamber.
  17. taliv

    taliv Moderator

    1858, just my opinion, but i think it accurately measures changes in pressure. but like any tool, it's only as good as it can be calibrated and the guesswork comes in how an individual would go about calibrating it AND the assumptions made about the barrel material.

    all the strain gage does is measure the resistance in a wire. As the wire is stretched, the resistance changes. The wire is stretched because it is epoxied to some steel. the steel stretches with pressure.

    so... to use it, you have to input the thickness of the steel at the midpoint of the chamber. Do you have a tool to MEASURE the inside of the chamber at that point? or are you going off what the book says it should be? of course, the entire premise of my assertion is that the ID changes with wear on the reamer, and thus pressure changes. So if you didn't measure it... well, garbage in, garbage out. and how well can you measure it? measure it 10 times and see if your high and low are a couple thou apart. will a couple thou make a difference? my guess is yeah.

    how much of a difference is there in CMV and stainless, 4140 vs 4150, 440 or whatever? i don't know. maybe they're all the same. maybe not. do they expand differently at different temperatures? i don't know that either. my guess is probably a little.

    the way i calibrated the tool was to purchase factory ammo (this method only works for calibers that offer factory ammo, and my interest was primarily in wildcats though) then call the factory and give them the lot number and ask what their pressure was. so to calibrate, i would shoot 3-5 rounds of factory ammo, and then enter a fudge factor to move the graph to where the factory said it should shoot, then shoot my handloads and compare them to the factory.

    of course, that method only applies to that one barrel, but i was only interested in tailoring loads to that one barrel, not trying to get my junior mythbusters badge
  18. MCMXI

    MCMXI Well-Known Member

    In the article the author states ....

    "All gauges were attached at the midpoint of the case, which is where SAAMI tests pressures;"

    This is incorrect. SAAMI specifies that the transducer is located much closer to the shoulder when testing bottleneck cartridges and very close to the heel of the bullet when testing straight-walled cartridges ... see page 133.

  19. taliv

    taliv Moderator

    nice catch. i didn't know that.

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