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Thread: to crimp or not to crimp...that is the question

  1. #1

    to crimp or not to crimp...that is the question

    Who does and why?
    Did you have a problem before you started doing it?
    Did it produce the results you wanted?
    Do you do it only on bullets with cannelures?

    From what I understand the neck tension despite being very important is a consequence of brass quality and bullet size. I.E. the brass will resize to the size of the bullet when seated and the amount of tension is dependant on inherent strength and flexibility in the brass in that case neck.
    I can see how softer brass could produce less neck tension and harder brass produce more.

    I get how any variance neck thickness can produce different tension just through having more brass in the neck

    I am not sure physically how a crimp can impart more tension unless the bullet has a cannelure in which case it is forming a tighter "lip" in the groove and ultimately
    restricts your seating depth to that level.
    Or the crimp is slightly crushing the bullet jacket in which case either the neck is going to be slightly thinner there or the bullet is going to have a microscopic waist from the crimp.


    thoughts from the educated for one eager to know more....

  2. #2
    This was talked about a while ago try a search as i could'nt do a link .

  3. #3
    I read one on neck tension and thought there was something here a while ago but am b@ggered if I could find it?
    anyone have a link?

  4. #4
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    On the advice of a professional reloader and all round shooting guru, I stopped crimping early in my reloading career.

    Whether the way I had crimped prior to this caused any inaccuracies or not I really cannot say as many things were happening simultaneouly. e.g. I was shooting more, I was coming to grips with consistent reloading and so forth. However, I've never felt the need to go back to crimping and firmly believe that all I could hope to do now is introduce yet another possible source of variabilty to my reloading and to do that seems counter-intuitive and undesirable to me.

    The short answer has to be; go with what you find works for you.

    BTW, I believe that crimping without a cannelure always risks deforming the bullet. Can that ever be good?

  5. #5
    Doh!
    Found it - To crimp or not to crimp

    still it doesnt actually answer any of the questions of
    1) why did people start? i.e what was the problem
    2) the restrictions of crimping at a cannelure depth vs with bullets without a cannelure.

    very few of mine have cannelures.

    I suspect i will give it a go and see what happens!

  6. #6
    never crimped, but maybe just go for a high quality of brass such as lapua, buy in bulk of 100. use them 10 times and bin them. I'd think that should offer consistent enough neck tension for stalking, probably even for BR...but I'm not knowledgable in crimping, so just throwing this in the mix as a suggestion which surely can be torn apart!

  7. #7
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    Sorry, shold have answered your question better.

    Crimping (consistently) will tend to equalise start pressures in much the same way as careful managment of neck tension, though it does tend to mean that higher start pressures will arise.

    Factory ammunition makers like having ways of dialing out the production variables and equalising start pressure through crimping can help. However, the by products of crimping i.e. having higher start pressures and hopefully better equalised velocities doesn't always deliver more accuracy.

    Can a handloader deliver equal and even crimp pressure like the machines in factories? Or, as I already said, is it just another source of variabilty that the handloader doesn't need to get into... suck it and see.

  8. #8
    I crimp frequently. I only use Lee Factory Crimp dies with uniformly trimmed brass. If your brass isn't the same length, you're wasting your time. Don't brain work it. Try it if you have the mind. Ammunition is crimped all the time. All pistol ammo is crimped. Most factory rifle ammo is crimped. All .22 RF ammo is crimped. It's been happening for a very long, long time. At worst it will do no good for you, at best, it will tighten your groups.~Muir

  9. #9
    Quote Originally Posted by Muir View Post
    Don't brain work it. Try it. At worst it will do no good for you, at best, it will tighten your groups.~Muir
    best answer I have read yet!
    thinking about stuff too much..thats my problem.

    will see what it does

  10. #10
    Quote Originally Posted by Muir View Post
    I crimp frequently. I only use Lee Factory Crimp dies with uniformly trimmed brass. If your brass isn't the same length, you're wasting your time. Don't brain work it. Try it if you have the mind. Ammunition is crimped all the time. All pistol ammo is crimped. Most factory rifle ammo is crimped. All .22 RF ammo is crimped. It's been happening for a very long, long time. At worst it will do no good for you, at best, it will tighten your groups.~Muir
    X2

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