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Thread: Powder Weights

  1. #1

    Powder Weights

    This might seem a strange question and the world might fall on me, but I see members quoting load weights of powder in fractions of a grain (to the tenth of a grain) does this make a differance or are they just being anal

  2. #2
    Quote Originally Posted by sikadog View Post
    This might seem a strange question and the world might fall on me, but I see members quoting load weights of powder in fractions of a grain (to the tenth of a grain) does this make a differance or are they just being anal
    I'll bet everyone was waiting for me to answer this one before JAYB got into the act! The answer to the question is....

    Probably, but not necessarily so.

    As I am always fond of mentioning, world class bench rest shooters do NOT weigh each charge yet they shoot the most accurate rifles in the world. They usually throw a charge straight from the powder measure to the case mouth and seat a bullet. So if they can do this, what justification is there for a fellow shooting a field grade Howa .243 to spend time weighing each charge?!??

    This is why.

    When the powder they are using doesn't meter well through the measure and the spread between minimum and maximum is small. Let's face it, if the Starting charge of powder X is 42 grains and the Max is 44 grains and there is a 300 fps spread in velocity and a 10K spread in pressure, you'd best not be off by a half a grain. In this circumstance, weighing is appropriate. What is not appropriate is the powder. If you are held to these constraints you generally have a "peaky" powder that is too fast for the bullet / cartridge and you should consider something less volatile the next time you choose powder. I have a tiny wildcat cartridge called the 5mm Craig. With all powders I MUST weigh each charge as a .1 grain difference is 100 fps with some of the best powders. Even with some super accurate measures in my possession I still need to eliminate that margin. If I could come up with a powder that would deliver the velocity I need and didn't require weighing I'd be all over it.

    Bench rest shooters use powders that meter well and don't require more than the accuracy they get from their fine measures.

    With stalking cartridges which usually have a larger case capacity than the BR cartridges, and nowhere near the uniformity of brass and bullets in the component chain, the powders tend to be slower and less sensitive to small variances in powder charge. With IMR 4831 for example, the burning rate is slow enough so that in most cartridges, weighing to a tenth of a grain is senseless. In fact, a full grain will do little to effect grouping. There is too much variance from cartridge case to cartridge case with regards to neck tension and case capacity and any advantage you might have seen by weighing is negated. To take this to the absurd degree, it is perfectly safe to take 5010 powder (for 50 cal machinegun powder) and scoop a 30-06 case full, shake off a bit, and crunch a bullet into the case. Shoots great.

    So some people might say that if there are so many variables in case capacity and neck tension then weighing powder will help negate the ill effects. It might, but it's unlikely. You are just as likely to end up with identical performance... especially if you're using a slower powder in a stalking cartridge sized case.

    So. If you are using peaky powders, weigh. If you are segregating your cases with regards to volume and are achieving even pull weight (neck tension), weigh: you might see a difference.

    Hell. If you just WANT to weigh each charge, do so. If time is worth something, look hard at your load and decide whether or not you need to weigh each charge. ~Muir
    Last edited by Muir; 26-03-2010 at 00:15.

  3. #3
    Thanks for the fantastic answer it was aimed at you, I read as much in the Lee 2nd edition loading book but its great to have it comfirmed with much more detail.

  4. #4
    Another thank you, but to you both. I am a novice reloader so I liked the question! And I loved the answer, practical and sound advice!!

    Many thanks, ft
    Blindness to suffering is an inherent consequence of natural selection. Nature is neither kind nor cruel but fiercely indifferent.

  5. #5
    You're both welcome. I hate weighing charges. JAYB came out here once and I lent him my custom Ruger #1 single shot .223. At 200M was yanking pint-sized prairiedogs out of their holes (which means he was having to hit a half pint!) using loads that were loaded with Lee Dippers. And that from a rest made from a camera tripod. I loaded my daughters ancient Winchester 243 this last fall using H414 and dippers. When she zeroed her rifle she tacked three shot groups in the 5/8" MOA class. I load 6.5x55 with 4530 using the same method. In fact, I don't weigh ANY hunting charges as I don't weigh and segregate brass, nor do I prep hunting brass other than to trim and after loading, crimp if appropriate. OF course, if a hunting rifle shoots MOA I'm tickled pink. Under MOA is better but not necessary. My 7x57 shoots half MOA but I can't shoot much better than about 4 MOA standing so it doesn't matter.~Muir

  6. #6
    Just read through and i thought i would reply just to bring it back up,very useful,,,,,,,as i was weighing bullets ie 100gr 120gr 140gr just to check if there is much difference between them from the same box,after calibrating my 502 scales,you can tell i need something to do right!,still none the wiser but hey beats talking to her indoors .

  7. #7
    I was taught to reload by a friend who goes beyond fussy, when it comes to measuring powder. He has medical scales that weigh to three decimal places of a grain, and I've seen him cut individual grains of powder to get his exact load !

    To be fair, he's into long range vermin shooting, and I've seen him shot a rabbit at 807m, but even so, I'm not certain a few grains of powder either way, can make much difference ?

    That said, his approach rubbed off on me, to some extent. My scales weigh to two decimal places, and only recently have I started allowing loads to be +/- .02 of a grain

    It's really hard to get out of the mind set. Just what fluctuation makes no odds, and it's really not so difficult to get it very close.................. I think I may need help, is there a "RA" group I can go to

  8. #8
    Quote Originally Posted by Lateral View Post
    He has medical scales that weigh to three decimal places of a grain, and I've seen him cut individual grains of powder to get his exact load
    I've done the very same thing with H4831

    Guess I better get that stick out of my ass and unclench after reading Muir's great reply
    A Man should be wise, but never too wise. He who does not know his fate in advance is free of care

  9. #9
    All good points but it doesn't really tell the whole story... I've done plenty of load development over the years and am surrounded by load developing in my target shooting club.. the SOP is to move up to target load in 0.3gn increments and either use the ladder method or just separate targets and observe the results... groups can vary from 3" to almost single holes.. once the best performers have been identified, the process is repeated around the better groups but this time in 0.1gn increments... again, group size will vary.. once the most promising group is identified, you can then start experimenting with seating depth to see if that can make things better.

    A couple of things to mention about benchrest shooters.. 1. barrel weight... the main cause of group size discrepancies is barrel harmonics... by changing the charge weight, the harmonic is altered.. the goal is to match the frequency of the bang with the resonant frequency of the barrel to either minimise vibration or ensure the bullet leaves the muzzle at the same point in the resonant cycle... the lighter the barrel, the more flexible it will be and therefore any flex and movement will be greater... benchrest barrels tend to be huge, thick, incredibly heavy and therefore stiff and less prone to changes in harmonic frequencies... quite a few also use large adjustable weighting systems on the muzzle to counteract the effects too.. 2. the powder measures benchrest shooters use tend not to be your common or garden 50 unit... Harrels precision meters for example are capable of pretty much 0.1gn accuracy.. they also cost .

    In conclusion... I understand the sentiment that 'it's a hunting rifle, it doesn't need to be sub MOA' etc... in practical terms, that is true... doesn't make it right though.. if it can be made to shoot sub moa then why wouldn't you? it gives more confidence, it reduces the chance of a bad shot and it is kinder to the beast you are shooting. I'm lucky in that my rifle shoots the factory ammo I use in cloverleaf, which is perfectly acceptable.. I would rather they all pretty much went through the same hole like they do with my target rifle but I am fully aware that even the best lightweight sporting barrel has limitations. But to say that +/- .1 or .2 grains won't make any noticeable difference is, in my experience, totally wrong!
    Last edited by Vipa; 13-09-2016 at 08:33.

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