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Thread: Why more powder for 223 than 556

  1. #21
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    Quote Originally Posted by triggerjerk View Post
    Hornady 62gr website download data shows more powder in 223 for 2230 and xbr than for 556 and equal max loads for TAC. Emailed em and they simply said lab said that where pressure got high.

    Would someone explain to this fudd how that works?
    Because every barrel is a law unto itself. You can take two identical barrels that came off the assembly line next to each other and they can exhibit completely different behaviors when it comes to pressure, velocity, precision and ammo preference.

    Every reloading book carries the warning to never start with max loads, but to start at least 10% under and work up watching carefully for pressure signs. They give the same warning anytime a change is made, such as switching primers from one brand to another. It does seem odd that a 5.56 chamber would reach peak pressure before a 223 barrel, but it's possible. One possibility is that the 223 wasn't cut to true SAAMI spec. I suspect that most makers of 223s deliberately cut the throats long to keep shooters from blowing something up shooting 5.56 ammo.
    Last edited by MistWolf; 09-10-21 at 22:42.
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  2. #22
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    Hornady email reply simply said checked with lab and that was where pressure spiked high. Accurate's response was that they couldn't speak as to why Hornady switched the data, but the respondent had used Hornady data in the past with no problems. No response from either to further inquiry of other instances or why.

    Guess I'll continue to survey multiple sources and work up towards medium moderate published max for given components.

    40 years ago, it was so much easier to just buy Sierra, reference my Sierra manual, immediately load my 30/06 to max, and blast away at deer.... Oh, well.

  3. #23
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    I've experimented with charge weights outside recommendations made by bullet companies and powder companies and I have experienced overpressure situations. In short, I am lucky I did not blow myself up. If a recommended charge weight will expose Hornady to civil liability, Hornady won't recommend it.
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  4. #24
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    Quote Originally Posted by T2C View Post
    I've experimented with charge weights outside recommendations made by bullet companies and powder companies and I have experienced overpressure situations. In short, I am lucky I did not blow myself up. If a recommended charge weight will expose Hornady to civil liability, Hornady won't recommend it.
    Hornady has had plenty of their own factory ammo kaboom 5.56 rifles. Some of those owners with blown up stuff do threads about their experience and share pictures...

    Guess who Hornady usually blames in those cases.

  5. #25
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    On max charge load data:


    I’ve watched max loads being changed multiple time. One of which was 6.5-284 when another company came out with their hot new 6.5, suddenly the 6.5-284 couldn’t be loaded to the speed is used to safely. I wonder why?

    Was it that actual problems were being reported? Possible with several companies chambering the 6.5-284 in factory guns. Or was it to make the new round seem supreme for those looking at load data? Also could be true.

    One recent round I’ve been working with for the last two years is the 6.5 PRC. I managed to work it up to the published max charge. I was still slower than published velocity and had zero pressure signs. I worked up two full grains past published loads and never saw pressure. I also didn’t have the case density of published loads. Perhaps the brass changed? Doubtful. But I was using a load manual with their own 6.5mm competing with the 6.5 PRC.

    I wonder if the creation of the hotter 22s has been a reason to publish lower charges/speeds of old rounds to make the new 22s seem more appealing. Who knows with Hornady, but I wouldn’t put it past them to market in such a way.


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  6. #26
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    Quote Originally Posted by DG23 View Post
    Hornady has had plenty of their own factory ammo kaboom 5.56 rifles. Some of those owners with blown up stuff do threads about their experience and share pictures...

    Guess who Hornady usually blames in those cases.
    Factory ammunition fired in factory rifles that have not been modified?
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  7. #27
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    Couple of years ago I was gifted a pound of powder manufactured overseas. They only had spotty online load data. The guy who emailed response to my inquiry was very personable, but what they later published was a couple of grains less than what he quoted. I had no pressure signs tho and love their powder.

    I do sometimes wonder why more factory loads don't blow more factory rifles. Again, I'm not really a max chaser, but factory stuff always seems hotter than what I settle on. And the guns I have seen at the public range.....

    And I won't bash Hornady. Just last week I checked some 55fmj reloads against the tics on a new 1x8 scope on a 16 in Anderson (cough, cough) upper. At 400yds, minute and a half for 5 shots with 4 of them in 3/4 minute. No wind, but still not bad for an fmj bullet?....

    I do wish Accurate wasn't afraid to tell me exactly what their "62 'mil'" bullet was....
    Last edited by triggerjerk; 09-12-21 at 17:21.

  8. #28
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    Yes 5.56 is thicker brass thus holds less powder but pressures rise quickly !

  9. #29
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    Quote Originally Posted by T2C View Post
    Factory ammunition fired in factory rifles that have not been modified?
    I have witnessed on my Labradar single round velocity spikes of greater than 200fps with Frontier 68gr ammo in otherwise consistent strings of 10. This yielded velocities 180fps higher than (real, not XM) M855 fired through the same barrel, same day, same temp. This has happened twice, IIRC, in two different 5.56 marked barrels that both pass a Michiguns 5.56? Gauge and were in good condition, with a LMT E-Bolt. (Edit: at least 3 times. One of which was a “5.56 Match Mod 0” chamber with a Colt bolt. This barrel is old and starting to slow down.) I thought the first time was an equipment fluke, because it was an unbelievable number for factory ammo. Makes me wonder how many of these Project Eldest Son proof loads went un-measured before I realized it was no fluke.

    Quote Originally Posted by mRad View Post
    Case capacity also varies pretty drastically year to year, lot to lot. I seem to recall back in the mid-2000s a guy on a precision shooting forum measuring differences in LC stamp and seeing a .2 gr capacity difference from one year to the next. That’s over 5%.


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    Thank you, I was unaware that LC varied so much.
    Last edited by 1168; 04-10-22 at 09:48.

  10. #30
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    Quote Originally Posted by 1168 View Post
    I have witnessed on my Labradar single round velocity spikes of greater than 200fps with Frontier 68gr ammo in otherwise consistent strings of 10. This yielded velocities 180fps higher than (real, not XM) M855 fired through the same barrel, same day, same temp. This has happened twice, IIRC, in two different 5.56 marked barrels that both pass a Michiguns 5.56? Gauge and were in good condition, with a LMT E-Bolt. (Edit: at least 3 times. One of which was a “5.56 Match Mod 0” chamber with a Colt bolt. This barrel is old and starting to slow down.) I thought the first time was an equipment fluke, because it was an unbelievable number for factory ammo. Makes me wonder how many of these Project Eldest Son proof loads went un-measured before I realized it was no fluke.

    Thank you, I was unaware that LC varied so much.
    200 fps is a substantial spike. That can definitely cause a high flyer during a match. If the load is already on the high end of acceptable chamber pressure, that can cause an unpleasant surprise.

    I've never seen a spike like that with Hornady ammunition, but I haven't chronographed hundreds of rounds of one caliber of their ammunition. I generally chronograph 20 rounds (2 ten shot strings) of a particular cartridge if it groups well out of a rifle when I am trying to duplicate a factory load.
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