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Thread: reloading m855

  1. #1
    Team Gunsnet SILVER 05/2012 deth502's Avatar

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    reloading m855

    so, since the last post about an accuracy load for my bolt gun threw some doubt into the projectile selection, ive decided that since i have about 4k ss109's that i would try some of them out and see how a handloaded m855 would perform.

    i checked it out in the usgi specs and they specify the load to be 26.1gn of wc844. i plan on substituting the wc844 with some h335, which is damn near identical, if not just a tad bit colder than the wc844.

    checking out my load books, 26.1gn seems to be way too hot. my sierra manual has separate sections for bolt gun ammo and ar ammo, the bolt gun section has this in the safe load range, but the ar section, my speer manual and my hornaday manual both put it as at least 1gn over max.

    i am using cci 400 primers, so the cup is not as hard as a mil-spec primer which will only compound my problem, but im more worried about chamber pressures first over a possible pierced primer at this point.


    and again, disclaimer, i accept all responsibility for anything i load and no one should follow any advice contained in this thread ever, blah blah, blah...

    thoughts? experiences?

  2. #2
    Senior Member NAPOTS's Avatar

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    advice would be the standard stick with published loads, don't start at the max load, work your way up to the velocity that provides you with the best accuracy watching for signs of high pressure along the way. The most accurate load may not be the fastest by the way.

    I think you'll have better luck with the 68 gr hornady match bullets personally. My 1:8 barrel loves the 75gr version of that bullet.

    The M855 is loaded to 5.56mm NATO specs, most published data you are going to find is for .223 remmington.

  3. #3
    Team Gunsnet SILVER 05/2012 deth502's Avatar

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    true, i didnt think to take into account that the load data could be skewed between 223 and 5.56

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    Forum Administrator Schuetzenman's Avatar

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    Pretty good advise from NAPOTS is given. I usually start about .5 grains above the lower end of the spec listed on a cartridge / bullet combo. I will load 10 rounds, (enough for two 5 shot groups on paper) for a load to try. Example: the manual says 23 is a minimum load so I'll start at 23.5 grs. The next group will be .2 grains higher than that so 23.7 gr. average drop weight. Repeat making 10 rounds up until you get to maximum. I write down what the load size is, powder grade, primer on a slip of paper and put that in a zip lock sandwich bag along with the 10 rounds loaded. So I end up with a lot of baggies full of ammo each with a documented load paper inside.

    Take all that with the weapon to the range and then record in a notebook what each group is doing for accuracy. Be methodical and always take notes in the book on what you're doing.

    Lastly, M855 projectiles are not usually made with accuracy in mind. A quality non milspec bullet is going to give you a lot better results. I've shot the 68 gr. Hornaday bullet and for me it is significantly better than what the 62 gr. SS109 projectile will give in results.

    On the non milspec primers, in as much as you are using this load in a bolt action it isn't an issue. The AR / M16 platform has a free floating firing pin so a soft primer could allow for a slamfire. This is why the milspec primers are harder cups than standard primers. On the loads shown in the books lower than what you found for NATO spec M855. Remember 5.56 is not the same as .223. The chamber dimensions and how the lead and freebore in front of the chamber is longer and bigger. This prevents a high pressure spike that the SAAMI spec .223 chamber, (click the link below) will produce with a NATO spec. load. Said another way the NATO spec chamber is for machineguns and a lot of rounds to be fired quickly. .223 OTOH is designed for accuracy, the rifling is much closer to the chamber / case mouth in most cases. However, you don't want the bullet actually touching the rifling as that WILL case a huge pressure spike.

    http://www.saami.org/specifications_...tion/index.cfm

  5. #5
    Senior Member NAPOTS's Avatar

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    something I have to catch myself on is instinctively desiring the maximum velocity for any particular load, like it is horsepower in a car or something. If you are shooting paper there is no need at all to have the highest velocity for a particular bullet and powder combination, the paper doesn't care and the holes look the same a 2750 fps as they do at 2950 fps. As said earily a lot of times there is a sweet spot in velocity that produces the best groups with a given combination of components. For paper punching loads I usually just want the most accurate load I can muster up that will also reliably function in the firearm. With a bolt gun this is a non issue. My Ars also don't seem sensitive to bullet weight and velocity either.

    Hunting and defense ammo will most likely be different projectiles which are usually less accurate than match bullets. If you were using reloads for that purpose you can surely find a nice balance between velocity and accuracy.

    You might want to give Varget powder a try. I have found it very accurate in my .308 loads. You would be somewhere around 2600-2700 fps with the 68 gr bullet.

  6. #6
    Team Gunsnet SILVER 05/2012 deth502's Avatar

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    on primers, i realize the slam fire issue is not a concern with the bolt action, i was more coming at it from the angle of the harder cup will not want to flatten out and flow back into the firing pin recess, and/or possibly pierce, than the harder mil spec primer cups when the boundaries are being pushed.

    and i agree, i dont push for max load, i try for best accuracy. that said, i prefer the fastest most accurate load i can get, as a faster bullet makes range estimation less critical. but again, the whole point of this was not to push the limits on how much speed i can get out of it, to the contrary, i was questioning the basic, standard mil spec loading as published in the publication "ArmyAmmoSpecsTM43-0001-27"

    afa working up a load, my mo is to put all of the load data in my book, and differentiate the loads by head marking. black sharpie markings on the heads of the cartridges. ie, an "x" on the head is this load, nothing is this load, a "-" or "o" on the head are others, ect... ive found that markings on the sides of the cases can become obliterated upon firing, but the case heads seem fairly reliable.

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