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Thread: Load accuracy/powder charge

  1. #1

    Load accuracy/powder charge

    Not sure if this should be here or in Ballistics but here goes. I've developed a couple of loads for my .243 with 100 and 60gn bullets. Basically I started just above minimum load and worked up in half grains until I found the smallest group then stopped. Once I found which half grain increment shot the best I loaded rounds in .1gn increments either side of that and test fired to see which was most accurate. But my question is this...... If I had continued increasing the powder charge but obviously not exceeding maximum am I likely to find another accurate round as the velocity increases or is there usually just one sweat spot

  2. #2
    This won't help, but at the minute I'm finding the best group at 35.2gr and 36.6gr - make sense of that! It's a black art.

  3. #3

    As you increase the loads you may well find another sweet spot. I asked the same question of Steve Bowers, he reakons it is to do with barrel harmonics and that a rifle will have a number of 'sweet spots' all the way through the velocity ranges. If I were you I would keep experienting; including trying various powders and seating depths (most rifles seem to like between 0.002" and 0.007" jump to the lands, but this will depend on your magazine dimentions)... but then I enjoy mucking around with loads to see how they behave at the range

    Regarding maximum loads - these are not concrete; every book gives different maximums for the same calibre/bullet... the REALLY important thing it to learn to look for pressure signs in the cases. Often you can take loads way above the book max and see no pressure signs - though in my case it has never made any difference to accuracy...


  4. #4
    chops, thats interesting. I will try some more loads and i've currently seated my rounds 15thou of the lands. I have more magazine space so will try to reduce the gap and see what happens.

  5. #5
    I don't mean to sound harsh, but in my experience, working up loads to a tenth of a grain is senseless unless you are using a very "peaky" powder for the case in question or are running on the hight end. If you are using one of the slower powders you are really wasting time. Don't get me wrong: If you plan on weighing each charge, and that makes you feel good about your loads, then I wish you well. I remember when I did that, too. ~Muir

  6. #6
    Muir, I know what you are saying. But when I worked my first load up for the .243, 40.5gn of H4831sc shot the best of the .5gn increasing loads. I then loaded 40.3 through to 40.7 loads and retested. The 40.5 and 40.6 loads shot equally tight groups but there was a marked widening in the 40.4 and 40.7 groups. I settled on the 40.5gn loads under a 100gn Hornady spbt. I have tried several times to get my powder measure to throw consistent measures and I think it was yourself that suggested fitting a baffle to the powder hopper. This brought an increase in consistency but still leaves an average variation of around .4gn when using 4831sc. I have developed a load for 60gn bullets using H414 and found this powder to measure better. Now I just throw a short measure and trickle up to my intended load on the scales and yes it is slow.
    An tips on how to increase my speed with out loosing accuracy?

  7. #7
    MJR: Not really. It either shoots or it doesn't at a given speed and pressure. Do you own a chronograph? I've forgotten if you mentioned it. I would have been very interested to see what the actual velocity spread was between that 40.4 and 40.7 grain charge. Less than a half grain variance with that powder is usually meaningless which is why I like 4831 very much. I have enough cartridges for which I must weigh to a tenth of a grain as it is. I'm not a big H414 fan so I can't tell you about that one in the 243. Remember that factory ammunition (which is generally very accurate considering it must work in all guns and give reasonable results) is loaded with volumetric charges of powder. I doubt if they hit a half grain consistently.

    I used to weigh every charge, for every rifle load I shot. It gave me an elevated feeling of confidence and seemed to shoot better than thrown charges. When I got interested in bench rest shooting I was shocked to learn that NOBODY weighed charges while loading at the bench. They used a good volumetric measure instead. After that I started to rethink my position on weighing charges. Now, when it's appropriate, I weigh. Otherwise I toss them. For loads of 4831 in hunting rifles, I scoop them with Lee Dippers when I can, and card off the excess. I have not noticed a falling off of accuracy in these loads.

    My most precisely loaded, every day load is for 22 Hornet. I shoot quite a bit of it and my targets are very small so extreme accuracy is needed. I use a fine powder (Lil Gun, Hodgdons) and meter it through a Belding and Mull measure. It will throw within a tenth of a grain when there is a variance at all. As good as the B&M measure is though, it will still throw a .3 - .5 variance with 4831 but, as I mentioned, I think that is fine.~Muir

  8. #8
    No I don't have a chrony but I have been thinking about one for some time so I may invest. Your comments regarding the benchresters loading by volume is very interesting, I wonder if they can tell a diffeence between volume and weighed charges or just load by volume for convenience/speed? I have little experience of H414 but I chose it as a, its a little faster than 4831 and b, my local gunshop had it in stock! I suppose it meatures better because of its shape.

  9. #9
    MJR: A chronograph is really essential for load development: at least if you experiment. I have long felt that shooting without one is like shooting blind. (JMHO, of course.)

    BR shooters do load development with a scale... I don't want to mislead anyone there... but there is really no need to weigh charges provided the charge is sane and you've got a reliable measure. It must work for them because they... well... hold all the records, right?? For me it was a lesson learned.~Muir

  10. #10
    So presumably benchresters work up a weighed load then have a quantity measure to provide the same charge? I can see the logic in that, thanks.
    Now off to look for a chrony.....

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