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Different loads for same weight?

Discussion in 'Handloading and Reloading' started by hobbeeman, Jan 17, 2006.

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  1. hobbeeman

    hobbeeman Member

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    I am new to reloading, as will quickly become obvious. Why is there a different load of the same powder for lead vs jacketed bullets of the same weight? Is there a mathmatical formula used to adapt a powder for the different bullet compositions?

    For example: I have found a recipe for using Unique for 200gr jacketed bullets but no such recipe for 200gr lead in the manuals or on the Alliant website.

    Isn't the main thing the weight of the bullet and the pressures for each weight?

    Thanks,
    Hobbeeman
     
  2. shu

    shu Member

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    for me, one of the most satisfying outcomes of taking up reloading is gaining an understanding of the why's of the various components - fast vs slow powders, heavy vs light bullets, etc.

    lead bullets, excepting some particularly hard alloys, are usually kept at or below 1000 ft/sec muzzle velocity else lead vaporizes or melts off the base and builds up in the barrel.

    copper jacketed bullets avoid the leading problem, but being harder have more resistance against the steel barrel.

    in my speer #13 book the 38spl lead bullet loads are generally limited by the velocity cap; for copper jacketed bullets by pressure. in some cases only one powder wt is given for copper jacketed; more powder would be in danger of overpressure, less powder would present danger of bullet sticking in barrel.
     
  3. hobbeeman

    hobbeeman Member

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    I did not realize that this was a possibility. What would happen if a bullet stuck in a barrel? Would the gas then escape towards the shooter?

    How does the speed of burn affect the pressures? For example, It seems that if a powder is going to produce a certain amount of pressure, it will do it at any speed of burn...a cumulative effect, like blowing up a balloon. Is this not right?
     
  4. superhornet

    superhornet Member

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    Just for starters find a 2nd edition of Lee Loading manual. Gives many loads for lead bullets...
     
  5. Ol` Joe

    Ol` Joe Member

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    Copper and lead have different lubrisity (sp?) and the bearing surface of the bullets add to the way they resist the pressure. How deep each is seated, distance from the lands of the barrel, alloy used, all add up also. Weight is just one factor in how much pressure a load developes.

    The pressure will vent in the path of least resistance. If that is toward the shooter then yes.

    The burn speed of the powder is simply a measure of how fast that powder will burn in relation to another in a certain lab setting. The lab uses a "caloric bomb" to deduce this and the result has realy little value to a handloader. The burn rate will change in various cartridges, and isn`t a definate figure. The speed a powder burns in a 45acp may be faster then in a 9mm. If you look at a few charts the labs find different rates for the same powders in some cases.
    The pressure also tries to keep riseing until the powder has all burnt. As long as there is still powder, gas is still being produced. Different powder will not only burn at different rates but some powders will produce higher total amounts of gas for the same charge weight. they don`t react in any kind of linier measure. The movement of the bullet down the barrel adds volume to the area under pressure and helps keep pressure under control. Any glich or change in bullet movement will cause pressure to rise as it is now not being vented as the gas volume increases.

    Try picking up a Vihta vuori (sp?) powder manual. They have a very good detailed section on powders and their burning. The A-Square manual if you can find one is another very good manual for the explainations of causes and effects of component change and powders. Midway USA had both the last time I was at their web site. Don`t worry about the data just read the text and get a good understanding of what is accuring and how to use your tools to produce safe, accurate ammo.

    Its only kinda rocket science.......:D:D
     
  6. snuffy

    snuffy Member

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    Excellent post Joe! I would add that the softer lead bullet will obturate,(slug up), sealing the bore more completely, thus raising pressure. Jacketed bullets tend to not obturate as easily, so some of the powder gases blow past the bullet, acting like a pressure relief.

    Leading occurs easily with soft swaged lead bullets above 1,000 fps. Adding tin and antimony to the cast lead bullets, like scrap wheelweight lead, will allow their use at past 1,000 fps. If you are talking about a 45 acp here,(you didn't mention caliber), you won't be going past 1,000 fps, so it's a moot point. Some of the hot magnums can and do get past the 1,000 fps boundry, so harder cast lead bullets are usefull up to 1,500 fps.
     
  7. snuffy

    snuffy Member

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    Excellent post Joe! I would add that the softer lead bullet will obturate,(slug up), sealing the bore more completely, thus raising pressure. Jacketed bullets tend to not obturate as easily, so some of the powder gases blow past the bullet, acting like a pressure relief.

    Leading occurs easily with soft swaged lead bullets above 1,000 fps. Adding tin and antimony to the cast lead bullets, like scrap wheelweight lead, will allow their use at past 1,000 fps. If you are talking about a 45 acp here,(you didn't mention caliber), you won't be going past 1,000 fps, so it's a moot point. Some of the hot magnums can and do get past the 1,000 fps boundry, so harder cast lead bullets are usefull up to 1,500 fps.

    Forgive the double post, WHAT NO DELETE FEATURE ON THE EDIT SCREEN???????¿
     
  8. Vern Humphrey

    Vern Humphrey Member

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    No. The great danger of a bullet sticking in the barrel is that you might not realize it and fire a second shot. That would be disasterous -- and even experienced shooters have been known to fail to realize the last bullet didn't exit.

    That might be if the power were in a sealed container. Buit what happens is the bullet starts to move, and the gas expands, with a resulting drop in pressure. If the powder burns at too low a speed it will never "catch up" -- and may not all burn.

    A good example of this would be a revolver round with insufficient crimp -- the pressure never gets to build up before the bullet starts to move. The result is poor accuracy and unburned grains of powder found in the chamber and bore.
     
  9. hobbeeman

    hobbeeman Member

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    So if someone is finding unburn powder on the table after firing at the range, this is a good indication that either the rate of burn is too slow, or that they have not crimped the load hard enough?
    Hobbeeman
     
  10. Vern Humphrey

    Vern Humphrey Member

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    Those are the first two things I'd check if I were finding unburned powder.
     
  11. countertop

    countertop Member

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    Will increasing the crimp increase the rate of burn?

    I had lots of powder on the table when I went to the range the other day - I was shooting my first batch of reloads. I subsequently increased (by 1 turn of the die) the crimp (haven't measured it yet, my caliper arrives from midway today).

    Is there anything else to change the rate of burn? Will different primers impact the rate? Do different amounts of powder burn diffrently? FWIW - I am using Unique and CCI 300 primers to load .45 ACP (230 grain Georgia Arms .451 caliber FMJs)

    Accuracy wasn't great, rounds were mostly landing a 6 inches low or so at 15 yards.

    This is a very helpful thread, thanks!
     
  12. t0066jh

    t0066jh Member

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    Mathematical Formula

    So, part of the original question was "Is there a mathmatical formula used to adapt a powder for the different bullet compositions?"

    Is there. How do you adjust if you must?
     
  13. ArchAngelCD

    ArchAngelCD Member

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    Since we are talking about powder burn rate I thought it might be a help if I posted a file with all the powders in order of burn speed. I got this from a site, saved it in a Wordprocessor and then converted to Adobe format so everyone can use it. I hope it's a help to those who are starting out in reloading.
     

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  14. gwalchmai

    gwalchmai Member

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    No, there is not. Worse, different alloys have different friction characteristics and different bullet shapes have different bearing surfaces, all of which make them more or less "slick" running down your barrel, which has unique characteristics itself.

    Therefore the best rule of thumb is to use your manual as a guide, start with the lowest loads and work your way up, watching for pressure signs along the way. And avoid the upper limit loads for the first year you're loading.
     
  15. redneck2

    redneck2 Member

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    Well, kinda. If you have a little slower powder (being relative to pistol), the force from the primer can start the bullet down the barrel unless it's crimped. If the bullet is pushed out by the primer before the powder lights off, there is too much volume for the burning powder to build heat/pressure. You'll get unburned powder. The slower the powder, the more common this is.

    Powder type and lot, primer brand, magnum or regular primer, amount of crimp, ambient temperature, interior case volume, bullet type, bullet seating depth, revolver vs autoloader, and bullet brand are some of the things that affect pressure.

    IMO, Unique is one that's harder to get a good burn because it's a relatively slow powder. You'll probably be OK with the 230/45acp combo because it's a heavy bullet and you'll fill most of the case. I use AA#5 or Universal Clays and they're a lot cleaner. VV powders are supposed to be super clean.
     
  16. wcwhitey

    wcwhitey Member

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    Unique is a medium burning powder of sorts. Slower than 231 but not as slow as 2400 or the like. I use it and and really like it for lead bullets that can be heavy crimped for the reasons stated by Mr. Humphrey. It is great for general purpose medium power rounds in Magnums or standard velocity/pressure rounds in .38 Special, 44 Special, .45 Colt and .45 ACP. I does not like low pressure loadings, 231 is better for such things. For full power Magnum rounds the slower burning powders are better like 2400/296/H110. When I load expensive jacketed bullets I do not generally use Unique as it is hard to get the ballistics that can be had from the slower burning powders and therefore almost seems like I am throwing away money. Universal Clays is a close cousin of Unique in it's burn rate. It has been around a long, long time for good reason, just certain tricks that bring out its best side. Bill
     
  17. Mark whiz

    Mark whiz Member

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    Some powders are just more prone to leaving a few stray unburned grains laying around on the table. Hodgdon Universal Clays is one. I've shot it in .38Spcl, .357Mag, .32ACP, and .45ACP and it always leaves behind a trail of powder, no matter how heavy of a crimp I use.
     
  18. Walkalong

    Walkalong Moderator

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    There are many Powder Burn Rate charts if you search them out and powders move up and down on them quite a bit. Burn rates of powders changes as the conditions change. They can be generally listed in approximate order of burn rate, but that is all. All the powder companys will tell you not to use a burn rate chart to guestimate charges and Speer manual #13 left a burn rate chart out intentionally.

    It is not as confusing as it seems though. Get a couple of good manuals and read, read, read.

    The Lyman manual mentioned above is an excellent one if you intend to load a lot of lead.

    Bullet weight, crimp, case volume, bullet type, bullet diameter, slow vs medium vs fast powder, all help determine how a powder is going to behave in any one caliber.

    Follow the manuals and you will be fine. For any one application there will usually be several powders which will work well. We all have our favorites of course.
     
  19. Snapping Twig

    Snapping Twig Member

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    Don't forget gas checks! All my magnum loads have 'em, .357 - .44 and the Casull. They work!

    I find that you get an extra 100fps, all other things being equal, for a lead bullet over a jacketed one.

    I use a 50/50 mix of Linotype and wheel weights with Alox lube.

    I read an article some years back where you could harden a bullet with an oven treatment, but I don't recall the specifics and it seemed a bit much to be honest when you can change the alloy much more easily.
     
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