Results 1 to 10 of 10

Thread: I just...never knew

  1. #1

    Question I just...never knew

    I just read that IMR powder (maybe applies to other brands as well?), regardless of name, all have the same energy per grain. It's just the cut (size) and it's coating that determines the burning rate. So, same powder, only different shape and coating? Huh.
    If you like getting kicked by a mule...then you'll "love" shooting my .458.

  2. #2
    Member marshall's Avatar
    Join Date
    Nov 2007
    Location
    Near Phoenix, AZ
    Posts
    1,814

    Default

    Quote Originally Posted by Maydog View Post
    I just read that IMR powder (maybe applies to other brands as well?), regardless of name, all have the same energy per grain. It's just the cut (size) and it's coating that determines the burning rate. So, same powder, only different shape and coating? Huh.
    Where did you read that?

    Can you post that piece of material?

  3. #3
    Sponsor ADfields's Avatar
    Join Date
    Nov 2008
    Location
    Missing Palmer AK in Phonix AZ.
    Posts
    6,416

    Default

    News to me!
    Andy
    On the web= C-lazy-F.co
    Email= Andy@C-lazy-F.co
    Call/Text 602-315-2406
    Phoenix Arizona

  4. #4
    Member
    Join Date
    Apr 2006
    Location
    SwampView AK, Overlooking Mt. Mckinley and Points Beyond.
    Posts
    8,816

    Default

    Size, shape, and coatings certainly do effect how a particular powder burns.

    I've always assumed that there is a difference in chemical composition between many powders.

    ?????

    Smitty of the North
    Walk Slow, and Drink a Lotta Water.
    Has it ever occurred to you, that Nothing ever occurs to God? Adrien Rodgers.
    You can't out-give God.

  5. #5
    Moderator
    Join Date
    Jan 2005
    Location
    Midwest
    Posts
    4,431

    Default

    Single base powders are made of nitro cellulose and some inert substances. The diameter, length, shape, perforation and deterrent coatings make the various burn rates. That's it. The extruded IMR series of powders are in this category, as are most other. Some extruded powders and most spherical powders have a small amount (5 to 15%) of nitro glycerine added as do some of the flake shaped powders. These are called double based, two active ingredients, but still rely on the shape, coatings, etc for burn rate. The yield strength of these double base powders and the pressure curve will have a different shape. Newer powder development, the higher energy powders are double base with some unique shaping and coating to maintain a flatter pressure curve. The RL-17 has it deterrent coating mixed into the body of the powder kernal, not just on the surface. This is supposed to limit the peak pressure but make the curve flatter.

    The Powley computer is developed for the IMR powders because they are of the same substance with just different shape, coating, etc. This makes the calculations more accurate.
    Is there nothing so sacred on this earth that you aren't willing to kill or die for?



  6. #6

    Default

    I would guess that for all single base powders which to my knowledge is cellulose (?spelling) or gun cotton that would be true. and may be simular for the double based with has the addition of nitroglycerin for added energy.

    Its all finding the best burn rate for time under pressure and it changes with each cartridge/bullet combo for all powders. Burn rates arn't constant everything effect them.

    Then there is cordite, Black powder and all the BP substitutes.

    I didn't type fast enough murphy bet me to it But with a much better answer.
    Last edited by tjen; 05-21-2009 at 08:38. Reason: update

  7. #7
    Moderator
    Join Date
    Jan 2005
    Location
    Midwest
    Posts
    4,431

    Default

    Quote Originally Posted by tjen View Post
    I would guess that for all single base powders which to my knowledge is cellulose (?spelling) or gun cotton that would be true. and may be simular for the double based with has the addition of nitroglycerin for added energy.

    Its all finding the best burn rate for time under pressure and it changes with each cartridge/bullet combo for all powders. Burn rates arn't constant everything effect them.

    Then there is cordite, Black powder and all the BP substitutes.

    I didn't type fast enough murphy bet me to it But with a much better answer.
    The quickest fingers in the west??/

    You bring out a very good point, this burning rate will vary (with the same powder) based on volume (case size) powder charge, bullet weight and chamber/barrel dimensions, even though it is the exact same powder used in the 223 or the 458 Win mag. So we need to be very scientific or follow the loading manuals very closely.
    Is there nothing so sacred on this earth that you aren't willing to kill or die for?



  8. #8

    Talking

    Quote Originally Posted by marshall View Post
    Where did you read that?
    I read that in the Hornady Handbook, 1967 printing on page 43. I know...must have been bored.
    If you like getting kicked by a mule...then you'll "love" shooting my .458.

  9. #9
    Member
    Join Date
    Nov 2006
    Location
    Missoula, MT
    Posts
    448

    Default

    thanks for teaching me something new; I was clueless. J.

  10. #10

    Wink

    I'm like Smitty...just assumed they were different chemically. Murphy knew all along though and that Cheshire grin says it all.
    If you like getting kicked by a mule...then you'll "love" shooting my .458.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •