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Thread: Compressed charge

  1. #1

    Compressed charge

    Ok so my latest issue with reloading is......

    I have prepared my cases by fl resizing trimming to book trim length chamfering and re-priming.
    i have prepared a dummy round to book length which fits rifle and magazine well.

    im now ready to fill the cases with powder in half grain steps from book start of 43gn to book max of 48gn.

    i was just checking what the max load looked like in the case and it's flush with the case mouth!
    to get a charge that is down below the neck (ie won't be compressed when I seat the bullet) I have to go down to 45gn).

    do I just go from start load to 45gn and avoid compressing loads or do I go all the way up to book max and squash the powder in with the bullets (this concerns me a little).

    all the best,
    mike
    Last edited by palmer_mike; 10-10-2014 at 13:02.

  2. #2
    I use a drop tube when I am loading compressed charges. It helps get a few more grains in the case.

    https://dl.dropboxusercontent.com/u/...ing%20good.jpg

    The load still needs to be worked up carefully.

    The alternative and I suspect what the majority will recommend, is to pick a powder that doesn't result in overfilling the case.

    Regards

    JCS

  3. #3
    In case it makes any difference this is in .308win with 150gn hornady interlock. Federal once fired brass, fl resized and trimmed to book length. Powder is imr 4064.
    using the lyman book I'm working on a start of 43gn and max of 48gn........

  4. #4
    Quote Originally Posted by palmer_mike View Post
    In case it makes any difference this is in .308win with 150gn hornady interlock. Federal once fired brass, fl resized and trimmed to book length. Powder is imr 4064.
    using the lyman book I'm working on a start of 43gn and max of 48gn........
    Change the book.

    The Lyman manual is an antique. My Hornady Manual stops at a MAX of 44.9.
    If I'm going to be accused of it then it's just as well I did it.

  5. #5
    Quote Originally Posted by Sinistral View Post
    Change the book.

    The Lyman manual is an antique. My Hornady Manual stops at a MAX of 44.9.
    Which would seem to fit with what the case can hold without compressing the powder.........
    but imr load data also gives start and maximum the same as the lyman book.

    the lyman book does say the maximum charge would be compressed, I'm just surprised about the amount I'd have to compress it to get the bullet in!

    also I was told to go for the data from the powder manufacturer as the most reliable.....

    now unsure of what to do, might start at lyman/imr start load and stop at 45gn (which would not be compressed (a lot less rounds to test, lol)

  6. #6
    Have you been testing progressively and getting no signs of pressure up until the compressed loads Mike, or are you loading a wide range of loads including the compressed loads in anticipation of testing them all at once?
    If the second is the case then you might just get a satisfactory load long before you need to go that far and may end up pulling them.
    It's the calibre of the shooter that counts not the calibre of the rifle.

  7. #7
    Quote Originally Posted by palmer_mike View Post
    Which would seem to fit with what the case can hold without compressing the powder.........
    but imr load data also gives start and maximum the same as the lyman book.

    the lyman book does say the maximum charge would be compressed, I'm just surprised about the amount I'd have to compress it to get the bullet in!

    also I was told to go for the data from the powder manufacturer as the most reliable.....

    now unsure of what to do, might start at lyman/imr start load and stop at 45gn (which would not be compressed (a lot less rounds to test, lol)
    There are so many variables.... for instance if you use Norma cases rather than Fed you can get a couple more grains in.

    I've used 47.5grs IMR 4064 in these (level with neck base) with a Sierra SP following the Speer Handbook, but using an OAL of 2.82".

    45.0grs only made 2600 FPS.
    If I'm going to be accused of it then it's just as well I did it.

  8. #8
    SD Regular NorthDorset's Avatar
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    Interesting fact. Over the 20 years I have been reloading the manufacturers have got far more cautious and I notice a lot of loads are now presented at reduced strength. Obviously afraid of litigation.

    JCS here probably presents the simple answer in choosing a powder that fills the case better. 8X57 as usual makes good sense. I use VHT N140 usually. Lots of folks on here have moved to TR140 which usually required about 1Gr more.

    Compressed loads by reputation are scary to work with as a novice but so long as you go carefully as you have described then you should be fine. (CAVEAT: You must be sure what you are doing is safe)

    Work up slowly looking for signs of pressure. Flattened or cratered primers are usually the first indication.

    Frankly you don't have to go nuts on a load with decent accuracy to shoot 100yd Deer. 1000 Yard target loads are a different animal all together.
    Last edited by NorthDorset; 10-10-2014 at 13:47.
    Yes I should have taken the Blue Pill!

    We were so busy congratulating ourself of dodging Orwells vision we marched right into Huxley's.

  9. #9
    Quote Originally Posted by 8x57 View Post
    Have you been testing progressively and getting no signs of pressure up until the compressed loads Mike, or are you loading a wide range of loads including the compressed loads in anticipation of testing them all at once?
    If the second is the case then you might just get a satisfactory load long before you need to go that far and may end up pulling them.
    The second option,
    I'm just preparing loads so I can test them progressively when I can next get use of a range for a few hours.

  10. #10
    Quote Originally Posted by Sinistral View Post
    Change the book.

    The Lyman manual is an antique. My Hornady Manual stops at a MAX of 44.9.

    Lyman manual, an antique? You believe? Not for a second!

    Taking the Hornady load at face value, with a 2.800" (SAAMI) COAL (assuming that's just right for the chamber throat which is dubious with factory rifles, their freebore usually being MUCH longer these days), and fairly heavy (Lapua or RWS) brass, QuickLOAD says that you get all of 50,233 psi PMax with 44.9gn IMR-4064 and the 150gn Hornady Interlock SP #3031, compared to the cartridge's SAAMI MAP (maximum average pressure, ie peak is allowed to exceed that) of 60,191 psi - not quite an efficient load, even though it'll suffice for any British deer at short ranges and may give excellent results in terms of precision etc. However, a typical factory rifle typified by Remington 700s is usually given a large amount of freebore these days which further depresses pressures and velocities, so you'd be unlikely to achieve that modest 50,000 psi taking pressures back into what was regarded as the norm in the early days of smallbore military rifles and crude smokeless propellants around 120 years ago!

    A point which is constantly made in handloading manuals, and constantly ignored by most users, is that the combinations only apply when all listed components are used. In the Lyman data, that's a Remington case which comes from the factory pretty thin-walled and therefore with an enhanced internal capacity. For normal calculations and comparisons, as used for example in QuickLOAD, the exact case capacity is determined by weighing a fireformed unsized case empty followed by level-full with water to obtain the 'overflow water capacity', this then converted to volume in CCs. In my 'minimum-SAAMI' (ie 'tight') .308 match rifle chambers, the water capacity of fired cases varies from 56.0 to 57.4gn depending on make. In a relatively 'slack' factory rifle chamber, the Remington case capacity will be at least 57gn, possibly as high as 57.5gn, it being one of the thinnest on the market.

    Stick those values into QuickLOAD, and you get a 105.8% charge fill ratio (with seated bullet at 2.800" COAL) and 59,323 psi with a 57gn H2O capacity case, 104.8% charge fill ratio and a computed 58,113 psi for a 57.5gn case. With a decent length drop tube on the powder funnel, allied to a slow charge pour and obtaining a swirl motion in the funnel top, I would expect the actual powder compression to be modest in both examples.

    However, use the Lyman load with a heavy Lapua case, worse an IMI model at 56.0gn H2O capacity or less and things get a bit hairy with 108% fill-ratio and a PMax that exceeds the maximum allowed.

    If anything in this mix can be described as 'antique', it's the powder as IMR-4064 was introduced by DuPont Industries in 1935 for military smallarms cartridges (hence its name Improved Military Rifle) and has changed little since. It's one of the most versatile propellants in its class and usually gives superb results in cartridges with similar characteristics to .308 Win - that's why it's been around for nearly 80 years and still sells well.

    Right, what to do about powder up to the case-mouth? Mike, as JCS says use a modest length drop funnel - MTM does a reasonably priced multi-calibre kit incorporating a 4-inch funnel.

    http://www.mtmcase-gard.com/products...funnel-AF7.php

    Forster does a longer (and considerably more expensive) metal drop tube model

    http://www.forsterproducts.com/catal...?prodid=700677

    Both are available from Hannams Reloading Limited. The Forster funnel plus a slow / swirl pour will take the powder level down to the bottom of the neck. However, as noted, if you're using any case other than Winchester or Remington, drop that maximum load to 47gn anyway to take account of case volumes. As always, start well below and work up and look for good results rather than velocity for its own sake, unless you intend to take up 1,000 yard FTR match competition.

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