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Thread: slow and fast burning powders

  1. #1

    slow and fast burning powders

    Im trying to learn as much as possible before i embark on the world of reloading! Could anybody offer some advice on the difference between slow and fast burning powders and their different applications.
    I will be reloading for a .308 with 125gr bullets, and a .243 with 85gr bullets
    Are there certain powders that are best suited for these calibers.
    I have a few different reloading manuals and own the ABC's of reloading book and they all give many options for various loads but just wanted to know what the difference in the powders are and what applications to use them in.
    I hope this makes sense.

  2. #2
    I don't know the difference between fast and slow powders as it's something I've never even thought about. I've just picked up the Hornday Manual (8th Edition) and opened it on the 85-87 gr bullets for 243 Win page. I see 10 powders listed that will give me a maximum velocity of 3100 fps. I've scanned the list and see I've three of these powders in the cupboard.

    I know I can lay my hands on more N160 if I need, so that would be my pick of a powder this evening. As to fast or slow, it's academic to me. It's a technical detail that I'm letting Hornady worry about.

    Regards

    JCS

  3. #3
    They're all made of the same basic stuff, nitrocellulose and nitroglycerine. The burn rate is governed by the size and shape of the granules and the retardant coating that is applied. Slower powders have larger granules, normally. Generally the burn rate is matched to the cartridge characteristics, the bigger the cartridge then the slower the powder, plus the smaller the exit hole from the case versus the size of the body of the case, then the slower the powder you need. Taken to extremes, a .22 rimfire needs a fast powder, a .50 BMG case necked down to .22 would need a very slooow powder indeed. I'd recommend the Vihtavuori reloading manual for more details on powder characteristics, but in practical terms you just pick a powder recommended by the loading data and work up loads doing that. You don't necessarily get better loads using powders at one end of the fast-slow range for the cartridge. Sierra do show their best accuracy loads and best hunting loads, which can be useful.

  4. #4
    Quote Originally Posted by M275 View Post
    They're all made of the same basic stuff, nitrocellulose and nitroglycerine. The burn rate is governed by the size and shape of the granules and the retardant coating that is applied. Slower powders have larger granules, normally. Generally the burn rate is matched to the cartridge characteristics, the bigger the cartridge then the slower the powder, plus the smaller the exit hole from the case versus the size of the body of the case, then the slower the powder you need. Taken to extremes, a .22 rimfire needs a fast powder, a .50 BMG case necked down to .22 would need a very slooow powder indeed. I'd recommend the Vihtavuori reloading manual for more details on powder characteristics, but in practical terms you just pick a powder recommended by the loading data and work up loads doing that. You don't necessarily get better loads using powders at one end of the fast-slow range for the cartridge. Sierra do show their best accuracy loads and best hunting loads, which can be useful.
    I have just bought some second hand reloading equipment and included was some viht N140. So basically the best thing to do is to find the N140 load and work up from the minimum? Are there better powders than others or is it all rifle specific and down to personal preference? Thanks for the advice

  5. #5
    Quote Originally Posted by jcampbellsmith View Post
    It's a technical detail that I'm letting Hornady worry about.
    I think i may just do the same!

  6. #6
    Think of squeezing a water filled plastic bottle with a cork in the top
    you can gently but firmly squeeze it and force the cork out or you can squeeze it hard and fast by stamping on it.

    The tighter the cork = the heavier the bullet
    The faster you squeeze = the faster the powder

    Too fast and the pressure gets too high and the bottle pops!!

  7. #7
    Many of the reloading books have lists showing burn rates of powders.

    i'm loving the idea of the .22-50BMG.....May be a tad over-bored and probably only 50 shots per barrel though!

  8. #8
    If your reloading data or manual lists a load for N140 in the calibre you're using then you might as well try it first, since you have it. Start 10% below maximum (or use a recommended starting load) then work up towards the maximum checking each case as you go for pressure signs. Having done that then you can load batches of 3 or 5 per tested load then see if they group. If you can get access to a chrono then you could check velocities too, but this is more benchrest or F-Class than stalking. Looking through the Sierra manual virtually every powder is a "best" choice for some combination of calibre and bullet weight, so there aren't better or worse powders in general terms. We all have our personal preferences, but powder supplies are so limited from the US these days that we're all having to try substitutes for our favourites. Even the dedicated 308 accuracy shooters seem to disagree on which powder to use, Reloder 15, N140, N540 and Varget are often preferred, but no-one's proved that one is better than another.

  9. #9
    Quote Originally Posted by Dorsettaff View Post
    Many of the reloading books have lists showing burn rates of powders.

    i'm loving the idea of the .22-50BMG.....May be a tad over-bored and probably only 50 shots per barrel though!
    Try googling it, it exists..!

  10. #10
    Quote Originally Posted by M275 View Post
    If your reloading data or manual lists a load for N140 in the calibre you're using then you might as well try it first, since you have it. Start 10% below maximum (or use a recommended starting load) then work up towards the maximum checking each case as you go for pressure signs. Having done that then you can load batches of 3 or 5 per tested load then see if they group. If you can get access to a chrono then you could check velocities too, but this is more benchrest or F-Class than stalking. Looking through the Sierra manual virtually every powder is a "best" choice for some combination of calibre and bullet weight, so there aren't better or worse powders in general terms. We all have our personal preferences, but powder supplies are so limited from the US these days that we're all having to try substitutes for our favourites. Even the dedicated 308 accuracy shooters seem to disagree on which powder to use, Reloder 15, N140, N540 and Varget are often preferred, but no-one's proved that one is better than another.
    Thanks, I have done a fair bit of research and a lot of people have suggested N140 for .308 so i guess i will start with this and see my results. It is an absolute minefield for a novice but i think i am hooked before i have even begun!

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